Method, UE and Basestation for Reporting/Receiving HARQ ACK/NACK for PDSCH in Dynamic TDD Configurations

ABSTRACT

The present disclosure relates to a method used in a User Equipment (UE) for reporting Hybrid Automatic Repeat Request (HARQ) acknowledgement (ACK)/non-acknowledgement (NACK) for Physical Downlink Shared Channels (PDSCHs) in dynamic time division duplex (TDD) configurations. In the method, a plurality of PDSCHs are received in DownLink (DL) subframes associated with an UpLink (UL) subframe and indicated by a DL reference TDD configuration. The DL subframes are divided into a first subset of DL subframes and a second subset of DL subframes. The first subset of DL subframes is also indicated by an UL reference TDD configuration. A first set of Physical Uplink Control Channel (PUCCH) resource indices are assigned based on resources used in transmission of Physical Downlink Control Channels (PDCCHs) corresponding to the PDSCHs received in the DL subframes of the first subset of DL subframes. A second set of PUCCH resource indices are assigned based on resources used in transmission of PDCCHs corresponding to the PDSCHs received in the DL subframes of the second subset of DL subframes. For each of the received PDSCHs, HARQ ACK/NACK is reported by using PUCCH resources in an order of the assigned first set of PUCCH resource indices for PDSCHs received in the DL subframes of the first subset of DL subframes and in an order of the assigned second set of PUCCH resource indices for PDSCHs received in the DL subframes of the second subset of DL subframes. The present disclosure also relates to a UE and BS for respectively reporting and receiving HARQ ACK/NACK for PDSCHs in TDD configurations.

PRIORITY

This application is a continuation of U.S. application Ser. No.14/780,034 filed on Sep. 25, 2015 entitled “Method, UE and Basestationfor Reporting/Receiving HARQ ACK/NACK for PDSCH in Dynamic TDDConfigurations”, which is a U.S. National Stage Filing under 35 U.S.C.§371 of International Patent Application Serial No. PCT/SE2014/050423filed Apr. 5, 2014, and entitled “Method, UE and Basestation forReporting/Receiving HARQ ACK/NACK For PDSCH in Dynamic TDDConfigurations” which claims priority to International PatentApplication Serial No. PCT/CN2013/073779 filed Apr. 5, 2013, all ofwhich are hereby incorporated by reference in their entirety.

TECHNICAL FIELD

The technology presented in this disclosure generally relate to radiocommunication networks, particularly, though not exclusively, radiocommunication networks using Time Division Duplex (TDD), for exampleLong-Term Evolution (LTE) TDD. More particularly, the present disclosurerelates to a method and user equipment (UE) reporting Hybrid AutomaticRepeat Request (HARQ) acknowledgement (ACK)/non-acknowledgement (NACK)for Physical Downlink Shared Channel (PDSCH) in dynamic time divisionduplex (TDD) configurations and a method and Base Station (BS) receivingHARQ ACK/NACK for PDSCH in dynamic TDD configurations.

BACKGROUND

This section is intended to provide a background to the variousembodiments of the technology described in this disclosure. Thedescription in this section may include concepts that could be pursued,but are not necessarily ones that have been previously conceived orpursued. Therefore, unless otherwise indicated herein, what is describedin this section is not prior art to the description and/or claims ofthis disclosure and is not admitted to be prior art by the mereinclusion in this section.

In a typical cellular radio system, user equipments (UEs) cancommunicate via a radio access network (RAN) to one or more corenetworks (CN). The RAN generally covers a geographical area which isdivided into radio cell areas. Each radio cell area can be served by abase station, e.g., a radio base station (RBS), which in some networksmay also be called, for example, a “NodeB” (UMTS) or “eNodeB” (LTE). Aradio cell is a geographical area where radio coverage is generallyprovided by the radio base station at a base station site. Each radiocell can be identified by an identity within the local radio area, whichis broadcast in the radio cell. The base stations communicate over theair interface operating on radio frequencies with the UEs within rangeof the base stations. In some radio access networks, several basestations may be connected, for example by landlines or microwave, to aradio network controller (RNC) or a base station controller (BSC). Theradio network controller may be configured to supervise and coordinatethe various activities of the plurality of base stations connectedthereto. The radio network controllers may also be connected to one ormore core networks.

The Universal Mobile Telecommunications System (UMTS) is a thirdgeneration mobile communication system, which evolved from the GlobalSystem for Mobile Communications (GSM). The Universal Terrestrial RadioAccess Network (UTRAN) is essentially a radio access network usingWideband Code Division Multiple Access (WCDMA) for UEs. As analternative to WCDMA, Time Division Synchronous Code Division MultipleAccess (TD-SCDMA) could be used. In a standardization forum known as theThird Generation Partnership Project (3GPP), telecommunicationssuppliers propose and agree upon standards for third generation networksand UTRAN specifically, and investigate e.g. enhanced data rate andradio capacity. The 3GPP has undertaken to evolve the UTRAN and GSMbased radio access network technologies. The first releases for theEvolved Universal Terrestrial Radio Access Network (E-UTRAN)specification have been issued. The Evolved Universal Terrestrial RadioAccess Network (E-UTRAN) comprises the Long Term Evolution (LTE) andSystem Architecture Evolution (SAE). Long Term Evolution (LTE) is avariant of a 3GPP radio access technology where the radio base stationnodes are connected to a core network, e.g., via Access Gateways (AGWs),rather than to radio network controller (RNC) nodes. In general, in LTEthe functions of a radio network controller (RNC) node are distributedbetween the radio base stations nodes (eNodeB's in LTE) and AGWs. Assuch, the radio access network (RAN) of an LTE system has what issometimes referred to as a “flat” architecture including radio basestation nodes without reporting to radio network controller (RNC) nodes.

Transmission and reception from a node, e.g., a radio terminal like a UEin a cellular system such as LTE, can be multiplexed in the frequencydomain or in the time domain, or according to combinations thereof. InFrequency Division Duplex (FDD), downlink (DL) and uplink (UL)transmission take place in different, sufficiently separated, frequencybands. In TDD, DL and UL transmission take place in different,non-overlapping time slots. Thus, TDD can operate in unpaired frequencyspectrum, whereas FDD generally requires paired frequency spectrum.

Typically, a transmitted signal in a radio communication system isorganized in some form of frame structure, or frame configuration. Forexample, LTE generally uses ten equally sized subframes 0-9 of length 1ms per radio frame as illustrated in FIG. 1. In case of TDD as shown inFIG. 1, there is generally only a single carrier frequency, and UL andDL transmissions are separated in time. Because the same carrierfrequency is used for UL and DL transmission, both the base station andthe UEs need to switch from transmission to reception and vice versa. Animportant aspect of a TDD system is to provide a sufficiently largeguard time where neither DL nor UL transmissions occur in order to avoidinterference between UL and DL transmissions. For LTE, specialsubframes, e.g., subframe #1 and, in some cases, subframe #6 asindicated by “S” in Table 1 below, provide this guard time. A TDDspecial subframe is generally split into three parts: a DL part (DwPTS),a guard period (GP), and an UL part (UpPTS). The remaining subframes areeither allocated to UL or DL transmission. Example UL-DL configurations,also referred to as “TDD configuration” in the present disclosure, areshown in Table 1 below where “U” indicates a subframe allocated to ULtransmission and “D” indicates a subframe allocated to DL transmission.Also, exemplary special subframe configurations are shown in Table 2below.

TABLE 1 Exemplary UL and DL configurations in TDD DL-to-UL Switch- UL-DLpoint Subframe number configuration periodicity 0 1 2 3 4 5 6 7 8 9 0 5ms D S U U U D S U U U 1 5 ms D S U U D D S U U D 2 5 ms D S U D D D S UD D 3 10 ms  D S U U U D D D D D 4 10 ms  D S U U D D D D D D 5 10 ms  DS U D D D D D D D 6 5 ms D S U U U D S U U D

TABLE 2 Example configurations of special subframe Normal cyclic prefixin DL Extended cyclic prefix in DL UpPTS UpPTS Normal Extended NormalSpecial cyclic cyclic cyclic Extended subframe prefix prefix prefix incyclic prefix configuration DwPTS in UL in UL DwPTS UL in UL 0  6592 ·T_(s) 2192 · T_(s) 2560 · T_(s)  7680 · T_(s) 2192 · T_(s) 2560 · T_(s)1 19760 · T_(s) 20480 · T_(s) 2 21952 · T_(s) 23040 · T_(s) 3 24144 ·T_(s) 25600 · T_(s) 4 26336 · T_(s)  7680 · T_(s) 4384 · T_(s) 5120 ·T_(s) 5  6592 · T_(s) 4384 · T_(s) 5120 · T_(s) 20480 · T_(s) 6 19760 ·T_(s) 23040 · T_(s) 7 21952 · T_(s) — — — 8 24144 · T_(s) — — —TDD allows for different asymmetries in terms of the amount of resourcesallocated for UL and DL transmission, respectively, by means ofdifferent DL/UL configurations. In LTE, there are seven differentconfigurations, see FIG. 2.

Generally speaking, to avoid significant interference between DL and ULtransmissions between different radio cells, neighboring radio cellsshould have the same DL/UL configuration. Otherwise, UL transmission inone radio cell may interfere with DL transmission in the neighboringradio cell and vice versa. As a result, the DL/UL asymmetry generallydoes not vary between radio cells. The DL/UL asymmetry configuration issignaled, i.e. communicated, as part of the system information and canremain fixed for a long time.

Consequently, the TDD networks generally use a fixed frame configurationwhere some subframes are UL and some are DL. This may prevent or atleast limit the flexibility to adopt the UL and/or DL resource asymmetryto varying radio traffic situations.

In future networks, it is envisioned that we will see more and morelocalized traffic, where most of the users will be in hotspots, or inindoor areas, or in residential areas. These users will be located inclusters and will produce different UL and DL traffic at different time.This essentially means that a dynamic feature to adjust the UL and DLresources to instantaneous, or near instantaneous, traffic variationswould be required in future local area cells.

TDD has a potential feature where the usable band can be configured indifferent time slots to either UL or DL. It allows for asymmetric UL/DLallocation, which is a TDD-specific property, and not possible in FDD.There are seven different UL/DL allocations in LTE, providing 40%-90% DLresources.

In the current networks, UL/DL configuration is semi-staticallyconfigured, thus it may not match the instantaneous traffic situation.This will result in inefficient resource utilization in both UL and DL,especially in cells with a small number of users. In order to provide amore flexible TDD configuration, so-called Dynamic TDD, also sometimesreferred to as Flexible TDD, has therefore been introduced. Thus,Dynamic TDD configures the TDD UL/DL asymmetry to current trafficsituation in order to optimize user experience. Dynamic TDD provides theability of a subframe to be configured as “flexible” subframe. As aresult, some subframes can be configured dynamically as either for ULtransmission or for DL transmission. The subframes can for example beconfigured as either for UL transmission or DL transmission depending one.g. the radio traffic situation in a cell. Accordingly, Dynamic TDD canbe expected to achieve promising performance improvement in TDD systemswhen there is a potential load imbalance between UL and DL. Besides,Dynamic TDD approach can also be utilized to reduce network energyconsumption. It is expected that dynamic UL/DL allocation, referred inthis section as “Dynamic TDD”, should provide a good match of allocatedresources to instantaneous traffic.

The UL scheduling can be indicated by Downlink Control Information (DCI)format 0 or Physical Hybrid Automatic Repeat Request (HARQ) indicatorchannel (PHICH) in a DL subframe, as described in Section 8 in the 3GPPTechnical Specification 3GPP TS 36.213, “Evolved Universal TerrestrialRadio Access (E-UTRA); Physical layer procedures”, v.11.1.0.

PUCCH HARQ-ACK resource allocation for PDSCH and ePDSCH has beenspecified in Rel-8 and Rel-11 respectively. For FDD a one to one mappingbetween the lowest Control Channel Element (CCE) index and PUCCHHARQ-ACK resource has been applied. In TDD, the challenge to PUCCHHARQ-ACK resource determination is the asymmetry between UL and DL,where there may for example be more DL subframes than UL subframesconfigured. This has been solved by allowing several DL subframes to bemapped to one UL subframe. The mapping of PUCCH resources for HARQ-ACKfeedback in the UL subframe will then be different depending on thenumber of DL subframes that are mapped to the UL subframe, i e dependingon the TDD configuration. For Dynamic TDD, when different UEs havedifferent TDD configurations, resource conflicts between UEs may occurin the UL mapping of PUCCH resources for HARQ-ACK feedback. WO2012/106840 discloses a method of dividing DL subframes into a first andsecond subset.

SUMMARY

It is thus an object of the present disclosure to provide an improvedmechanism for mapping of resources for PUCCH HARQ-ACK feedback. This isachieved by the claimed solution according to claims 1, 4, 7 and 10.

According to a first aspect of the present disclosure, a method used ina User Equipment (UE) for reporting Hybrid Automatic Repeat Request(HARQ) acknowledgement (ACK)/non-acknowledgement (NACK) for PhysicalDownlink Shared Channels (PDSCHs) in dynamic time division duplex (TDD)configurations is provided. The method comprises receiving a pluralityof PDSCHs in DownLink (DL) subframes associated with an UpLink (UL)subframe and indicated by a DL reference TDD configuration. The methodfurther comprises dividing the DL subframes into a first subset of DLsubframes and a second subset of DL subframes, wherein the first subsetof DL subframes is also indicated by an UL reference TDD configuration.The method further comprises assigning a first set of Physical UplinkControl Channel (PUCCH) resource indices based on resources used intransmission of Physical Downlink Control Channels (PDCCHs)corresponding to the PDSCHs received in the DL subframes of the firstsubset of DL subframes and assigning a second set of PUCCH resourceindices based on resources used in transmission of PDCCHs correspondingto the PDSCHs received in the DL subframes of the second subset of DLsubframes. Then, the method comprises: for each of the received PDSCHs,reporting HARQ ACK/NACK using PUCCH resources in an order of theassigned first set of PUCCH resource indices for PDSCHs received in theDL subframes of the first subset of DL subframes and in an order of theassigned second set of PUCCH resource indices for PDSCHs received in theDL subframes of the second subset of DL subframes.

According to a second aspect of the present disclosure, a method used ina User Equipment (UE) for reporting Hybrid Automatic Repeat Request(HARQ) acknowledgement (ACK) or non-acknowledgement (NACK) for PhysicalDownlink Shared Channels (PDSCHs) in dynamic time division duplex (TDD)configurations is provided. The method comprises: receiving a pluralityof PDSCHs in DownLink (DL) subframes associated with an UpLink (UL)subframe and indicated by a DL reference TDD configuration; and for eachof the received PDSCHs, reporting HARQ ACK/NACK by at least partiallyusing PUCCH resources indicated by Downlink Control Information (DCI)and/or Radio Resource Control (RRC) signaling.

As an example, the method further comprises: dividing the DL subframesinto a first subset of DL subframes and a second subset of DL subframes,wherein the first subset of DL subframes is also indicated by an ULreference TDD configuration; assigning a set of Physical Uplink ControlChannel (PUCCH) resource indices based on resources used in transmissionof Physical Downlink Control Channels (PDCCHs) corresponding to thePDSCHs received in the DL subframes of the first subset of DL subframes;for each of the PDSCHs received in the DL subframes of the first subsetof DL subframes, reporting HARQ ACK/NACK using PUCCH resources in anorder of the assigned set of PUCCH resource indices; and for each of thePDSCHs received in the DL subframes of the second subset of DLsubframes, reporting HARQ ACK/NACK using PUCCH resources indicated byDCI and/or Radio Resource Control (RRC) signaling.

According to a third aspect of the present disclosure, a method used ina User Equipment (UE) for reporting Hybrid Automatic Repeat Request(HARQ) acknowledgement (ACK) or non-acknowledgement (NACK) for PhysicalDownlink Shared Channels (PDSCHs) in dynamic time division duplex (TDD)configurations is provided. The method comprises: receiving a pluralityof PDSCHs in DownLink (DL) subframes associated with an UpLink (UL)subframe and indicated by a DL reference TDD configuration; for each ofthe received PDSCHs, determining a Physical Uplink Control Channel(PUCCH) resource based on resources used in transmission of PhysicalDownlink Control Channels (PDCCHs) corresponding to the PDSCHs receivedin the corresponding DL subframe and a start position of the PUCCHresource corresponding to the DL subframe; and reporting HARQ ACK/NACKusing the determined PUCCH resource.

According to a fourth aspect of the present disclosure, a method used ina User Equipment (UE) for reporting Hybrid Automatic Repeat Request(HARQ) acknowledgement (ACK) or non-acknowledgement (NACK) for PhysicalDownlink Shared Channels (PDSCHs) in dynamic time division duplex (TDD)configurations is provided. The method comprises: receiving a pluralityof PDSCHs in DownLink (DL) subframes associated with an UpLink (UL)subframe and indicated by a DL reference TDD configuration; selecting aDL subframe of the DL subframes, to be a first DL subframe, the sequencenumber of the selected DL subframe being the same as that of a first DLsubframe of DL subframes associated with the UL subframe but indicatedby an UL reference TDD configuration; assigning Physical Uplink ControlChannel (PUCCH) resource indices based on resources used in transmissionof PDCCHs corresponding to the PDSCHs received in the DL subframesassociated with the UL subframe and indicated by the DL reference TDDconfiguration, wherein the PUCCH resource indices are assigned in anorder starting from the selected first DL subframe of the DL subframesassociated with the UL subframe and indicated by the DL reference TDDconfiguration; and for each of the received PDSCHs, reporting HARQACK/NACK using PUCCH resources in the order of the assigned PUCCHresource indices.

According to a fifth aspect of the present disclosure, a User Equipment(UE) for reporting Hybrid Automatic Repeat Request (HARQ)acknowledgement (ACK)/non-acknowledgement (NACK) for Physical DownlinkShared Channels (PDSCHs) in dynamic time division duplex (TDD)configurations is provided. The UE comprises a receiver, a transmitter,a memory and a processor. The memory is configured to store TDDconfigurations. The processor is configured to control the receiver toreceive a plurality of PDSCHs in DownLink (DL) subframes associated withan UpLink (UL) subframe and indicated by a DL reference TDDconfiguration. The processor is configured to divide the DL subframesinto a first subset of DL subframes and a second subset of DL subframes,wherein the first subset of DL subframes is also indicated by an ULreference TDD configuration. The processor is configured to assign afirst set of Physical Uplink Control Channel (PUCCH) resource indicesbased on resources used in transmission of Physical Downlink ControlChannels (PDCCHs) corresponding to the PDSCHs received in the DLsubframes of the first subset of DL subframes. The processor isconfigured to assign a second set of PUCCH resource indices based onresources used in transmission of PDCCHs corresponding to the PDSCHsreceived in the DL subframes of the second subset of DL subframes. Theprocessor is configured to control the transmitter to, for each of thereceived PDSCHs, report HARQ ACK/NACK using PUCCH resources in an orderof the assigned first set of PUCCH resource indices for PDSCHs receivedin the DL subframes of the first subset of DL subframes and in an orderof the assigned second set of PUCCH resource indices for PDSCHs receivedin the DL subframes of the second subset of DL subframes.

According to a sixth aspect of the present disclosure, a UE forreporting Hybrid Automatic Repeat Request (HARQ) acknowledgement (ACK)or non-acknowledgement (NACK) for Physical Downlink Shared Channels(PDSCHs) in dynamic time division duplex (TDD) configurations isprovided. The UE comprises a receiver, a transmitter, a memory and aprocessor. The memory is configured to store TDD configurations. Theprocessor is configured to control the receiver to receive a pluralityof PDSCHs in DownLink (DL) subframes associated with an UpLink (UL)subframe and indicated by a DL reference TDD configuration. Theprocessor is configured to control the transmitter to, for each of thereceived PDSCHs, report HARQ ACK/NACK by at least partially using PUCCHresources indicated by Downlink Control Information (DCI) and/or RadioResource Control (RRC) signaling.

According to a seventh aspect of the present disclosure, a UE forreporting Hybrid Automatic Repeat Request (HARQ) acknowledgement (ACK)or non-acknowledgement (NACK) for Physical Downlink Shared Channels(PDSCHs) in dynamic time division duplex (TDD) configurations isprovided. The UE comprises a receiver, a transmitter, a memory and aprocessor. The memory is configured to store TDD configurations. Theprocessor is configured to control the receiver to receive a pluralityof PDSCHs in DownLink (DL) subframes associated with an UpLink (UL)subframe and indicated by a DL reference TDD configuration. Theprocessor is configured to, for each of the received PDSCHs, determine aPhysical Uplink Control Channel (PUCCH) resource based on resources usedin transmission of Physical Downlink Control Channels (PDCCHs)corresponding to the PDSCHs received in the corresponding DL subframeand a start position of the PUCCH resource corresponding to the DLsubframe. The processor is further configured to control the transmitterto, for each of the received PDSCHs, report HARQ ACK/NACK using thedetermined PUCCH resource.

According to a eighth aspect of the present disclosure, a UE forreporting Hybrid Automatic Repeat Request (HARQ) acknowledgement (ACK)or non-acknowledgement (NACK) for Physical Downlink Shared Channels(PDSCHs) in dynamic time division duplex (TDD) configurations isprovided. The UE comprises a receiver, a transmitter, a memory and aprocessor. The memory is configured to store TDD configurations. Theprocessor is configured to control the receiver to receive a pluralityof PDSCHs in DownLink (DL) subframes associated with an UpLink (UL)subframe and indicated by a DL reference TDD configuration. Theprocessor is configured to select a DL subframe of the DL subframes, tobe a first DL subframe, the sequence number of the selected DL subframebeing the same as that of a first DL subframe of DL subframes associatedwith the UL subframe but indicated by an UL reference TDD configuration.The processor is configured to assign Physical Uplink Control Channel(PUCCH) resource indices based on resources used in transmission ofPDCCHs corresponding to the PDSCHs received in the DL subframesassociated with the UL subframe and indicated by the DL reference TDDconfiguration, wherein the PUCCH resource indices are assigned in anorder starting from the selected first DL subframe of the DL subframesassociated with the UL subframe and indicated by the DL reference TDDconfiguration. The processor is configured to control the transmitterto, for each of the received PDSCHs, report HARQ ACK/NACK using PUCCHresources in the order of the assigned PUCCH resource indices.

According to a ninth aspect of the present disclosure, a method used ina Base Station (BS) for receiving Hybrid Automatic Repeat Request (HARQ)acknowledgement (ACK)/non-acknowledgement (NACK) for Physical DownlinkShared Channels (PDSCHs) in dynamic time division duplex (TDD)configurations is provided. The method comprises transmitting aplurality of PDSCHs in DownLink (DL) subframes associated with an UpLink(UL) subframe and indicated by a DL reference TDD configuration. Themethod further comprises dividing the DL subframes into a first subsetof DL subframes and a second subset of DL subframes, wherein the firstsubset of DL subframes is also indicated by an UL reference TDDconfiguration. The method further comprises assigning a first set ofPhysical Uplink Control Channel (PUCCH) resource indices based onresources used in transmission of Physical Downlink Control Channels(PDCCHs) corresponding to the PDSCHs transmitted in the DL subframes ofthe first subset of DL subframes and assigning a second set of PUCCHresource indices based on resources used in transmission of PDCCHscorresponding to the PDSCHs transmitted in the DL subframes of thesecond subset of DL subframes. Then, the method comprises: for each ofthe transmitted PDSCHs, receiving HARQ ACK/NACK on PUCCH resources in anorder of the assigned first set of PUCCH resource indices for PDSCHstransmitted in the DL subframes of the first subset of DL subframes andin an order of the assigned second set of PUCCH resource indices forPDSCHs transmitted in the DL subframes of the second subset of DLsubframes.

According to a tenth aspect of the present disclosure, a method used ina Base Station (BS) for receiving Hybrid Automatic Repeat Request (HARQ)acknowledgement (ACK) or non-acknowledgement (NACK) for PhysicalDownlink Shared Channels (PDSCHs) in dynamic time division duplex (TDD)configurations is provided. The method comprises: transmitting aplurality of PDSCHs in DownLink (DL) subframes associated with an UpLink(UL) subframe and indicated by a DL reference TDD configuration; and foreach of the transmitted PDSCHs, receiving HARQ ACK/NACK at leastpartially on PUCCH resources indicated by Downlink Control Information(DCI) and/or Radio Resource Control (RRC) signaling.

As an example, the method further comprises: dividing the DL subframesinto a first subset of DL subframes and a second subset of DL subframes,wherein the first subset of DL subframes is also indicated by an ULreference TDD configuration; assigning a set of Physical Uplink ControlChannel (PUCCH) resource indices based on resources used in transmissionof Physical Downlink Control Channels (PDCCHs) corresponding to thePDSCHs transmitted in the DL subframes of the first subset of DLsubframes; for each of the PDSCHs transmitted in the DL subframes of thefirst subset of DL subframes, receiving HARQ ACK/NACK on PUCCH resourcesin an order of the assigned set of PUCCH resource indices; and for eachof the PDSCHs transmitted in the DL subframes of the second subset of DLsubframes, receiving HARQ ACK/NACK on PUCCH resources indicated by DCIand/or RRC signaling.

According to a eleventh aspect of the present disclosure, a method usedin a Base Station (BS) for receiving Hybrid Automatic Repeat Request(HARQ) acknowledgement (ACK) or non-acknowledgement (NACK) for PhysicalDownlink Shared Channels (PDSCHs) in dynamic time division duplex (TDD)configurations is provided. The method comprises: transmitting aplurality of PDSCHs in DownLink (DL) subframes associated with an UpLink(UL) subframe and indicated by a DL reference TDD configuration; foreach of the transmitted PDSCHs, determining a Physical Uplink ControlChannel (PUCCH) resource based on resources used in transmission ofPhysical Downlink Control Channels (PDCCHs) corresponding to the PDSCHstransmitted in the corresponding DL subframe and a start position of thePUCCH resource corresponding to the DL subframe; and, for each of thetransmitted PDSCHs, receiving HARQ ACK/NACK on the determined PUCCHresource.

According to a twelfth aspect of the present disclosure, a method usedin a Base Station (BS) for receiving Hybrid Automatic Repeat Request(HARQ) acknowledgement (ACK) or non-acknowledgement (NACK) for PhysicalDownlink Shared Channels (PDSCHs) in dynamic time division duplex (TDD)configurations is provided. The method comprises: transmitting aplurality of PDSCHs in DownLink (DL) subframes associated with an UpLink(UL) subframe and indicated by a DL reference TDD configuration;selecting a DL subframe of the DL subframes, to be a first DL subframe,the sequence number of the selected DL subframe being the same as thatof a first DL subframe of DL subframes associated with the UL subframebut indicated by an UL reference TDD configuration; assigning PhysicalUplink Control Channel (PUCCH) resource indices based on resources usedin transmission of PDCCHs corresponding to the PDSCHs transmitted in theDL subframes associated with the UL subframe and indicated by the DLreference TDD configuration, wherein the PUCCH resource indices areassigned in an order starting from the selected first DL subframe of theDL subframes associated with the UL subframe and indicated by the DLreference TDD configuration; and for each of the transmitted PDSCHs,receiving HARQ ACK/NACK on PUCCH resources in the order of the assignedPUCCH resource indices.

According to a thirteenth aspect of the present disclosure, a BaseStation (BS) for receiving Hybrid Automatic Repeat Request (HARQ)acknowledgement (ACK)/non-acknowledgement (NACK) for Physical DownlinkShared Channels (PDSCHs) in dynamic time division duplex (TDD)configurations is provided. The BS comprises a receiver, a transmitter,a memory and a processor. The memory is configured to store TDDconfigurations. The processor is configured to control the transmitterto transmit a plurality of PDSCHs in DownLink (DL) subframes associatedwith an UpLink (UL) subframe and indicated by a DL reference TDDconfiguration. The processor is configured to divide the DL subframesinto a first subset of DL subframes and a second subset of DL subframes,wherein the first subset of DL subframes is also indicated by an ULreference TDD configuration. The processor is configured to assign afirst set of Physical Uplink Control Channel (PUCCH) resource indicesbased on resources used in transmission of Physical Downlink ControlChannels (PDCCHs) corresponding to the PDSCHs transmitted in the DLsubframes of the first subset of DL subframes. The processor isconfigured to assign a second set of PUCCH resource indices based onresources used in transmission of PDCCHs corresponding to the PDSCHstransmitted in the DL subframes of the second subset of DL subframes.The processor is configured to control the receiver to, for each of thetransmitted PDSCHs, receive HARQ ACK/NACK on PUCCH resources in an orderof the assigned first set of PUCCH resource indices for PDSCHstransmitted in the DL subframes of the first subset of DL subframes andin an order of the assigned second set of PUCCH resource indices forPDSCHs transmitted in the DL subframes of the second subset of DLsubframes.

According to a fourteenth aspect of the present disclosure, a BaseStation (BS) for receiving Hybrid Automatic Repeat Request (HARQ)acknowledgement (ACK) or non-acknowledgement (NACK) for PhysicalDownlink Shared Channels (PDSCHs) in dynamic time division duplex (TDD)configurations is provided. The BS comprises a receiver, a transmitter,a memory and a processor. The memory is configured to store TDDconfigurations. The processor is configured to control the transmitterto transmit a plurality of PDSCHs in DownLink (DL) subframes associatedwith an UpLink (UL) subframe and indicated by a DL reference TDDconfiguration. The processor is configured to control the receiver to,for each of the transmitted PDSCHs, receive HARQ ACK/NACK at leastpartially on PUCCH resources indicated by Downlink Control Information(DCI) and/or Radio Resource Control (RRC) signaling.

According to a fifteenth aspect of the present disclosure, a BaseStation (BS) for receiving Hybrid Automatic Repeat Request (HARQ)acknowledgement (ACK) or non-acknowledgement (NACK) for PhysicalDownlink Shared Channels (PDSCHs) in dynamic time division duplex (TDD)configurations is provided. The BS comprises a receiver, a transmitter,a memory and a processor. The memory is configured to store TDDconfigurations. The processor is configured to control the transmitterto transmit a plurality of PDSCHs in DownLink (DL) subframes associatedwith an UpLink (UL) subframe and indicated by a DL reference TDDconfiguration. The processor is configured to, for each of thetransmitted PDSCHs, determine a Physical Uplink Control Channel (PUCCH)resource based on resources used in transmission of Physical DownlinkControl Channels (PDCCHs) corresponding to the PDSCHs transmitted in thecorresponding DL subframe and a start position of the PUCCH resourcecorresponding to the DL subframe. The processor is further configured tocontrol the receiver to, for each of the transmitted PDSCHs, receiveHARQ ACK/NACK on the determined PUCCH resource.

According to a sixteenth aspect of the present disclosure, a BaseStation (BS) for receiving Hybrid Automatic Repeat Request (HARQ)acknowledgement (ACK) or non-acknowledgement (NACK) for PhysicalDownlink Shared Channels (PDSCHs) in dynamic time division duplex (TDD)configurations is provided. The BS comprises a receiver, a transmitter,a memory and a processor. The memory is configured to store TDDconfigurations. The processor is configured to control the transmitterto transmit a plurality of PDSCHs in DownLink (DL) subframes associatedwith an UpLink (UL) subframe and indicated by a DL reference TDDconfiguration. The processor is configured to select a DL subframe ofthe DL subframes, to be a first DL subframe, the sequence number of theselected DL subframe being the same as that of a first DL subframe of DLsubframes associated with the UL subframe but indicated by an ULreference TDD configuration. The processor is configured to assignPhysical Uplink Control Channel (PUCCH) resource indices based onresources used in transmission of PDCCHs corresponding to the PDSCHstransmitted in the DL subframes associated with the UL subframe andindicated by the DL reference TDD configuration, wherein the PUCCHresource indices are assigned in an order starting from the selectedfirst DL subframe of the DL subframes associated with the UL subframeand indicated by the DL reference TDD configuration. The processor isconfigured to control the receiver to, for each of the transmittedPDSCHs, receive HARQ ACK/NACK on PUCCH resources in the order of theassigned PUCCH resource indices.

By dividing the DL subframes into a first subset of DL subframes and asecond subset of DL subframes so that the first subset of DL subframesis also indicated by an UL reference TDD configuration and reporting(UE) or receiving (BS) HARQ ACK/NACK using PUCCH resources in an orderof the assigned first set of PUCCH resource indices for PDSCHs received(UE) or transmitted (BS) in the DL subframes of the first subset of DLsubframes according to at least the first, fifth, ninth and thirteenthaspects of the present disclosure, the above stated object is achievedin that conflicts in the UL mapping of PUCCH resources for HARQ feedbackbetween legacy UEs and dynamic-TDD-enabled UEs are avoided, so that theHARQ ACK/NACK transmissions from the legacy UEs and thedynamic-TDD-enabled UEs can be properly received at the base station.

Furthermore, by also reporting (UE) or receiving (BS) HARQ ACK/NACKusing PUCCH resources in an order of the assigned second set of PUCCHresource indices for PDSCHs received (UE) or transmitted (BS) in the DLsubframes of the second subset of DL subframes according to at least thefirst, fifth, ninth and thirteenth aspects of the present disclosure,the above stated object is achieved in that conflicts in the UL mappingof PUCCH resources for HARQ feedback between dynamic-TDD-enabled UEshaving different TDD configurations are avoided, so that the HARQACK/NACK transmissions from the dynamic-TDD-enabled UEs can be properlyreceived at the base station.

The above stated object is further achieved according to the second,sixth, tenth and fourteenth aspects of the present disclosure by atleast partially using PUCCH resources indicated by Downlink ControlInformation (DCI) and/or Radio Resource Control (RRC) signaling forreporting (UE) or receiving (BS) HARQ ACK/NACK feedback for PDSCHsreceived (UE) or transmitted (BS) in DL subframes associated with an ULsubframe and indicated by a DL reference TDD configuration, so thatdynamic-TDD-enabled UEs having different TDD configurations are informedby the network, e g the BS, of what PUCCH resources to use for HARQfeedback, thereby avoiding conflicts in the UL mapping of PUCCHresources for HARQ feedback, so that the HARQ ACK/NACK transmissionsfrom the dynamic-TDD-enabled UEs can be properly received at the basestation.

The above stated object is further achieved according to the third,seventh, eleventh and fifteenth aspects of the present disclosure byreporting (UE) or receiving (BS) HARQ ACK/NACK feedback, for PDSCHsreceived (UE) or transmitted (BS) in DL subframes associated with an ULsubframe and indicated by a DL reference TDD configuration, using PUCCHresources determined based on resources used in transmission of PDCCHscorresponding to the PDSCHs received (UE) or transmitted (BS) in thecorresponding DL subframe and a start position of the PUCCH resourcecorresponding to the DL subframe, so that dynamic-TDD-enabled UEs havingdifferent TDD configurations are able to determine what PUCCH resourcesto use for HARQ feedback in a uniform way, whereby conflicts in the ULmapping of PUCCH resources for HARQ feedback are avoided, so that theHARQ ACK/NACK transmissions from the dynamic-TDD-enabled UEs can beproperly received at the base station.

The above stated object is further achieved according to the fourth,eighth, twelfth and sixteenth aspects of the present disclosure byselecting a first DL subframe associated with the UL subframe andindicated by its sequence number in the DL reference TDD configurationas well as in the UL reference TDD configuration and reporting (UE) orreceiving (BS) HARQ ACK/NACK feedback, for PDSCHs received (UE) ortransmitted (BS) in DL subframes associated with the UL subframe andindicated by the DL reference TDD configuration, using PUCCH resourcesin an order indicated by PUCCH resource indices that are assigned basedon resources used in transmission of PDCCHs corresponding to the PDSCHsreceived (UE) or transmitted (BS) in the DL subframes in an orderstarting from the selected first DL subframe, so thatdynamic-TDD-enabled UEs having different TDD configurations are able todetermine what PUCCH resources to use for HARQ feedback in a uniformway. Because the PUCCH resource indices are assigned in an orderstarting from the selected first DL subframe, the order is alsocompatible with the UL mapping of PUCCH resources for HARQ feedbackapplied by legacy UEs, whereby conflicts in the UL mapping of PUCCHresources for HARQ feedback are avoided, so that the HARQ ACK/NACKtransmissions from the dynamic-TDD-enabled UEs as well as from legacyUEs can be properly received at the base station.

It is further an advantage of embodiments presented herein that whileHARQ feedback from dynamic-TDD-enabled UEs as well as legacy UEs can beproperly handled in environments where the TDD configuration of DL andUL subframes may vary dynamically in time and between UEs, the solutionsof presented embodiments also allow for efficiently compressing PUCCHHARQ ACK/NACK resources so that resource utilization efficiency may beimproved.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the presentinvention will be clearer from the following detailed description aboutthe non-limited embodiments of the present invention taken inconjunction with the accompanied drawings, in which:

FIG. 1 illustrates uplink/downlink time/frequency structure for LTE TDD;

FIG. 2 is a diagram illustrating an example of seven differentdownlink/uplink configurations for LTE TDD;

FIG. 3 illustrates an example TDD PUCCH HARQ-ACK resource allocationaccording to the prior art;

FIG. 4 shows example UL-DL configurations where UL-DL configuration 0 istaken as the UL reference TDD configuration;

FIG. 5 shows example PUCCH HARQ-ACK resource allocations;

FIG. 6 shows a flowchart of a method used in UE for reporting HARQACK/NAK for PDSCH in dynamic TDD configurations according to a firstembodiment of the present invention;

FIG. 7 illustrates an example of how the PUCCH HARQ-ACK resource can bestacked;

FIG. 8 illustrates an example of how the PUCCH HARQ-ACK resource can bestacked;

FIG. 9 shows a flowchart of a method used in UE for reporting HARQACK/NAK for PDSCH in dynamic TDD configurations according to a secondembodiment of the present invention;

FIG. 10 shows a flowchart of a method used in UE for reporting HARQACK/NAK for PDSCH in dynamic TDD configurations according to a thirdembodiment of the present invention;

FIG. 11 illustrates an example of how the PUCCH HARQ-ACK resources maybe stacked;

FIG. 12 shows a flowchart of a method used in UE for reporting HARQACK/NAK for PDSCH in dynamic TDD configurations according to a fourthembodiment of the present invention;

FIG. 13 illustrates an example of how the PUCCH HARQ-ACK resources maybe stacked;

FIG. 14 is a schematic block diagram of UE 1400 according to someembodiments of the present disclosure;

FIG. 15 is a schematic block diagram of UE 1500 according to someembodiments of the present disclosure;

FIG. 16 is a schematic block diagram of UE 1600 according to someembodiments of the present disclosure;

FIG. 17 is a schematic block diagram of UE 1700 according to someembodiments of the present disclosure;

FIG. 18 shows a flowchart of a method used in BS for receiving HARQACK/NAK for PDSCH in dynamic TDD configurations according to a fifthembodiment of the present invention;

FIG. 19 illustrates an example of how the PUCCH HARQ-ACK resource can bestacked;

FIG. 20 illustrates an example of how the PUCCH HARQ-ACK resource can bestacked;

FIG. 21 shows a flowchart of a method used in BS for receiving HARQACK/NAK for PDSCH in dynamic TDD configurations according to a sixthembodiment of the present invention;

FIG. 22 shows a flowchart of a method used in BS for receiving HARQACK/NAK for PDSCH in dynamic TDD configurations according to a seventhembodiment of the present invention;

FIG. 23 illustrates an example of how the PUCCH HARQ-ACK resources maybe stacked;

FIG. 24 shows a flowchart of a method used in BS for receiving HARQACK/NAK for PDSCH in dynamic TDD configurations according to a eighthembodiment of the present invention;

FIG. 25 illustrates an example of how the PUCCH HARQ-ACK resources maybe stacked;

FIG. 26 is a schematic block diagram of BS 2600 according to someembodiments of the present disclosure;

FIG. 27 is a schematic block diagram of BS 2700 according to someembodiments of the present disclosure;

FIG. 28 is a schematic block diagram of BS 2800 according to someembodiments of the present disclosure; and

FIG. 29 is a schematic block diagram of BS 2900 according to someembodiments of the present disclosure.

Throughout the drawings, the same or similar elements or steps areidentified by the same or similar reference signs.

DETAILED DESCRIPTION OF EMBODIMENTS

In the following, embodiments of the present invention will be describedin accordance with the drawings. In the following description, someparticular embodiments are used for the purpose of description only,which shall not be understood as any limitation to the present inventionbut merely examples thereof. While it may blur the understanding of thepresent invention, the conventional structure or construction will beomitted.

PUCCH HARQ-ACK resource allocation for PDSCH and ePDSCH has beenspecified in Rel-8 and Rel-11 respectively. However, PUCCH HARQ-ACKresource allocation when dynamic TDD is configured requires resourceconflictions for different UEs who have different TDD configurations tobe resolved if the current available PUCCH HARQ-ACK resource allocationschemes are to be used.

In TDD, the challenge to PUCCH HARQ-ACK resource determination is theasymmetry between UL and DL. When there are more DL subframes than ULsubframes, the one to one mapping between the lowest CCE index and PUCCHHARQ-ACK resource in FDD cannot be reused any more, since the PUCCHresources will collide with each other across different DL subframes. Onthe other hand, the HARQ-ACK resource utilization should be consideredsince the resources for PUSCH transmission will be reduced if excessiveUL resources are reserved for PUCCH HARQ-ACK transmission. The TDD PUCCHresource for HARQ-ACK transmission in response to legacy PDCCH has beenspecified in Section 8 in the 3GPP Technical Specification 3GPP TS36.213, “Evolved Universal Terrestrial Radio Access (E-UTRA); Physicallayer procedures”, v.11.1.0.

To give a detailed description for PUCCH resource for PDCCH, FIG. 3shows an example with four DL subframes and one UL subframe, whichcorresponds to TDD UL-DL configuration 2. The resource determination forHARQ-ACK multiplexing and HARQ-ACK bundling are similar and can bederived from Section 8 in the 3GPP Technical Specification 3GPP TS36.213, “Evolved Universal Terrestrial Radio Access (E-UTRA); Physicallayer procedures”, v.11.1.0. It can be seen that the PUCCH HARQ-ACKresources will be stacked firstly for the lowest CCE index of the DCIbelonging to the first one-third CCEs of the control region (marked withripples) across multiple subframes, denoted SF n-8, SF n-7, SF n-6 andSF n-4 in FIG. 3, followed by the DCIs belonging to second one-thirdCCEs (marked with inclined grids) and finally the last one-third CCEs(marked with panes). The design philosophy is that when the system loadis low, the control region could be automatically reduced by the dynamicsignaling of PCFICH, hence the PUCCH HARQ-ACK resource could becompressed to a continuous region.

When dynamic TDD is configured, in general, there are two UL-DLreference TDD configurations, one for UL and one for DL, as described inR1-130588, “Signaling Support for Dynamic TDD, Ericsson, ST-Ericsson.The UL reference TDD configuration is broadcasted in System InformationBlock 1 (SIB1) and will be used for legacy UEs. It can also be used forDynamic-TDD-enabled UEs for initial access. Based on the two referenceTDD configurations, some subframes may be used as flexible subframeswhere either DL or UL can be configured. When DL is configured in someflexible subframes, the DL reference TDD configuration will be assumedfor HARQ-ACK timing.

FIG. 4 shows an example where UL-DL configuration 0 is taken as the ULreference TDD configuration. In case subframe 4 and subframe 9 are usedas the flexible subframes, and they are configured as DL subframes, theDL reference TDD configuration is TDD configuration 1. Similarly, ifsubframe 3, 4, 8 and 9 are used as flexible subframes and are configuredas DL subframe, the DL reference TDD configuration is TDD configuration2.

In TDD, each UL subframe is associated with a set of DL subframes. TheHARQ-ACK in response to DL transmissions in these subframes shall betransmitted in the associated UL subframe. The DL association set isdefined as in Table 3, referring to Section 8 in the 3GPP TechnicalSpecification 3GPP TS 36.213, “Evolved Universal Terrestrial RadioAccess (E-UTRA); Physical layer procedures”, v.11.1.0.

TABLE 3 DL association set index K: {k₀, k₁, . . . k_(M−1)} for TDDUL-DL Subframe n Configuration 0 1 2 3 4 5 6 7 8 9 0 — — 6 — 4 — — 6 — 41 — — 7, 6 4 — — — 7, 6 4 — 2 — — 8, 7, 4, 6 — — — — 8, 7, 4, 6 — — 3 —— 7, 6, 11 6, 5 5, 4 — — — — — 4 — — 12, 8, 7, 11 6, 5, 4, 7 — — — — — —5 — — 13, 12, 9, 8, 7, 5, 4, 11, 6 — — — — — — — 6 — — 7 7 5 — — 7 7 —In case dynamic TDD is configured, some UEs, e.g., legacy UEs, will usethe UL reference TDD configuration for both UL and DL transmissions,whereas Dynamic-TDD-enabled UEs will use the UL reference TDDconfiguration for UL transmission and use the DL reference TDDconfiguration for DL transmissions. As a result, for legacy UEs, thePUCCH HARQ-ACK resource allocation is based on the UL reference TDDconfiguration; and for Dynamic-TDD-enabled UEs, the PUCCH HARQ-ACKresource allocation is based on DL reference TDD configuration. When theHARQ-ACK feedbacks occur in the same UL subframe, there will be PUCCHHARQ-ACK collisions between the legacy UEs and Dynamic-TDD-enabled UEs.

FIG. 5 shows example PUCCH HARQ-ACK resource allocations when the ULreference TDD configuration is TDD configuration 0 and DL referenceconfiguration is TDD configuration 2. For subframe 2, in configuration0, there is one associated DL subframe n-6 (subframe 6), and inconfiguration 2, there are four associated DL subframes n-8, n-7, n-4,and n-6 (corresponding to subframe 4, 5, 8 and 6). As shown in FIG. 5,PUCCH HARQ-ACK resource allocations for Configuration 0 are depicted inthe right and the PUCCH HARQ-ACK resource allocations for Configuration2 are depicted in the left. For the PUCCH resource allocation, it canseen that when the first one-third CCEs of subframe n-6 (i.e., theportion marked with ripples of SF n-6) are allocated for the legacy UE,and the first one-third CCEs of subframe n-8 (i.e., the portion markedwith ripples of SF n-8) are allocated for the Dynamic-TDD-enabled UEs,the PUCCH HARQ-ACK resources will collide with each other. In case ofconflict, i e if collision happens, HARQ-ACK transmission cannot beproperly received at the eNB.

Therefore, embodiments of the invention are provided to solve the abovetechnical problems.

First Embodiment

As the first embodiment of the invention, a method used in a UE forreporting HARQ ACK/NACK for PDSCH in dynamic TDD configurations isproposed.

In the method, referring to FIG. 6 which shows a flowchart of the method600, a plurality of PDSCHs are received in DL subframes associated withan UL subframe and indicated by a DL reference TDD configuration (Step610). The DL subframes are divided into a first subset of DL subframesand a second subset of DL subframes (Step 620). The first subset of DLsubframes is also indicated by an UL reference TDD configuration.Hereinafter, DL subframes associated with the UL subframe and indicatedby a UL reference TDD configuration may be referred to as the first DLassociation subframes of the UL subframe, and DL subframes associatedwith a UL subframe and indicated by a DL reference TDD configuration maybe referred to as the second DL association subframes of the ULsubframe. Thus, the first subset of DL subframes and the second subsetof DL subframes may be referred to as the first DL association subsetand the second DL association subset, respectively. Then, a first set ofPUCCH resource indices are assigned based on resources used intransmission of PDCCHs corresponding to the PDSCHs received in the DLsubframes of the first subset of DL subframes (Step 630), and a secondset of PUCCH resource indices are assigned based on resources used intransmission of PDCCHs corresponding to the PDSCHs received in the DLsubframes of the second subset of DL subframes (Step 640). Thereafter,for each of the received PDSCHs, HARQ ACK/NACK is reported by usingPUCCH resources in an order of the assigned first set of PUCCH resourceindices for PDSCHs received in the DL subframes of the first subset ofDL subframes and in an order of the assigned second set of PUCCHresource indices for PDSCHs received in the DL subframes of the secondsubset of DL subframes (Step 650).

In the present disclosure, there is an offset between the first set ofPUCCH resource indices and the second set of PUCCH resource indices. Theoffset herein may be configured by higher layers or predefined. Forexample, the offset may be notified by the eNB via RRC signaling orMedium Access Control (MAC) Control Element (CE).

In the present disclosure, the first set of PUCCH resource indices andthe second set of PUCCH resource indices may have different startpositions, which may be referred to as start positions of PUCCHresources. There are four alternatives for configuring respective startpositions:

As a first alternative, the eNB may broadcast respective startpositions.

As a second alternative, the eNB may notify a UE of the offset for thesecond DL association subset via RRC signaling or MAC CE once the UE isto be scheduled for DL data transmission in any flexible subframes;

As a third alternative, the eNB may broadcast offset(s) to indicate thestart position difference between different subsets of DL subframes,i.e., the start position difference between different sets of PUCCHresource indices, so that the UE can determine the PUCCH resources forthe second DL association subset based on the offset and start positionof the UL reference TDD configuration.

As a fourth alternative, the eNB may broadcast a start position of theUL reference TDD configuration. The UE determines the PUCCH resourcesfor the first DL association subset according to the received startposition and determines the PUCCH resources for the second DLassociation subset proportionally according to the amount of thefeedback of the two DL association subsets. In such case, the PUCCHresource start position for the second DL association set is just nextto the end position for the first DL association subset.

As a fifth alternative, the eNB may broadcast start position of the ULreference TDD configuration and the maximum size of PUCCH resources forthe UL reference TDD configuration. Similar to the fourth alternative,the PUCCH resource start position for the second DL association set isnext to the end position for the first DL association subset.

In some embodiments of the present disclosure, the steps of 630 and 640may be performed based on the following formula:

n _(PUCCH,i) ⁽¹⁾=(M _(q) −i−1)·N _(c) +i·N _(c+1) +n _(CCE,i) +N_(PUCCH) ^((q))   (1)

wherein n_(PUCCH,i) ⁽¹⁾ is a PUCCH resource index determined based onresources used in transmission of PDCCHs corresponding to the PDSCHsreceived in the DL subframe that is the i^(th) element of the q^(th)subset, M_(q) is the total number of DL subframes in the q^(th) subset,0≦i≦M_(g), c is selected from {0, 1, 2, 3} such thatN_(c)≦n_(CCE,i)<N_(c+1), N_(c) =max {0, └[N_(RB) ^(DL)·(N_(sc)^(RB)·c−4)]/36┘} where N_(RB) ^(DL) is the number of physical resourceblocks, PRBs, in each downlink subframe and where N_(sc) ^(RB) is thenumber of subcarriers in each physical resource block, n_(CCE,i) is thesequence number of the first Control Channel Element, CCE, used fortransmission of the corresponding PDCCH in subframe n−k_(i) ^((q)),k_(i) ^((q))(q=0,1) is the i^(th) element of the q^(th) subset, nindicates the UL subframe associated with the DL subframes where theplurality of PDSCHs are received, N_(PUCCH) ^((q)) (q=0,1) is an offsetfor q^(th) subset, wherein q=0 corresponds to one of the first andsecond subsets of DL subframes and q=1 corresponds to the other one ofthe first and second subsets of DL subframes. The offset may beconfigured by higher layers.

In some embodiments of the present disclosure, the second subset of DLsubframes may comprise all the DL subframes indicated by the DLreference TDD configuration other than DL subframes of the first subsetof DL subframes.

In some embodiments of the present disclosure, the first subset of DLsubframes may comprise one or more virtual subframes that are added bythe UE, and the one or more virtual subframes may be used only forassigning PUCCH resource indices, but not for real PDSCH transmissions.

In the following, some examples will be explained in detail by assumingthat the UL reference TDD configuration is TDD configuration 0 or TDDconfiguration 1 or TDD configuration 6, and the DL reference TDDconfiguration is TDD configuration 1or TDD configuration 2. In theseexamples, the subframes #3, #4, #8 and #9 are flexible subframes thatcan be allocated as UL and DL subframes.

EXAMPLE 1 TDD Configuration 1 (UL), TDD Configuration 2 (DL)

In this example, for UL subframe 2, the first DL association subset canbe {7, 6}, and the second DL association subset can be {8, 4}. Anexample DL association subset is shown in Table 4.

TABLE 4 Example DL association set index K: {k₀ ^((q)), . . . , k_(M)_(q)−1^((q))} for TDD when UL reference TDD configuration isconfiguration 1 and DL reference TDD configuration is 2 UL-DL Subframe nConfiguration 0 1 2 3 4 5 6 7 8 9 1 — — {7, 6} — 4 — — {7, 6} — 4 2 — —Subset 1: {7, 6} — — — — Subset 1: {7, 6} — — Subset 2: {8, 4} Subset 2:{8, 4}

FIG. 7 illustrates how the PUCCH HARQ-ACK resource can be stacked. Asshown in FIG. 7, subframes SF n-6 and SF n-7 not only belong toConfiguration 2 but also belong to configuration 1. Correspondingly, asshown in the left part of FIG. 7, their corresponding PUCCH HARQ-ACKresources may be stacked firstly. That is, PUCCH resource indices forPDSCHs received in the subframes SF n-6 and SF n-7 may be smaller thanthose for PDSCHs received in the remaining DL subframes. FIG. 7 is justan illustrative example, and the present disclosure is not limited tothis example. For example, PUCCH resource indices for PDSCHs received inthe subframes SF n-6 and SF n-7 may be larger than those for PDSCHsreceived in the remaining DL subframes. PUCCH HARQ-ACK resourcescorresponding to other DL association subframes may be stacked in asimilar way but with a separate offset (i.e., N_(PUCCH) ⁽¹⁾).

EXAMPLE 2 TDD Configuration 0 (UL), TDD Configuration 2 (DL)

In this example, for UL subframe 2, the first DL association subset is{6}, and the second DL association subset is {8,7,4}. An example DLassociation subset is shown in Table 5.

TABLE 5 Example DL association set index K: {k₀ ^((q)), . . . , k_(M)_(q)−1^((q))} for TDD when UL reference TDD configuration isconfiguration 0 and DL reference TDD configuration is 2 UL-DL Subframe nConfiguration 0 1 2 3 4 5 6 7 8 9 0 — — 6 — 4 — — 6 — 4 2 — — Subset 1:{6} — — — — Subset 1: {6} — — Subset 2: {8, 7, 4} Subset 2: {8, 7, 4}

FIG. 8 illustrates how the PUCCH HARQ-ACK resource can be stacked. Asshown in FIG. 8, subframe SF n-6 not only belongs to Configuration 2,but also belongs to Configuration 0. Correspondingly, as shown in theleft part of FIG. 8, their corresponding PUCCH HARQ-ACK resources may bestacked firstly. That is, PUCCH resource indices for PDSCHs received inthe subframe SF n-6 may be smaller than those for PDSCHs received in theremaining DL subframes. FIG. 8 is just an illustrative example, and thepresent disclosure is not limited to this example. For example, PUCCHresource indices for PDSCHs received in the subframe SF n-6 may belarger than those for PDSCHs received in the remaining DL subframes.PUCCH HARQ-ACK resources corresponding to other DL association subframesmay be stacked in a similar way but with a separate offset (i.e.,N_(PUCCH) ⁽¹⁾).

EXAMPLE 3 TDD Configuration 6 (UL), TDD Configuration 1 (DL)

In this example, for UL subframe 3, the first DL association subset is{7}, and the second DL association subset is {4}. An example DLassociation subset is shown in Table 6. As shown in Table 6, the secondDL association subset for UL subframe 3 contains no DL subframe havingthe same sequence number as that of any DL subframe in the first DLassociation subset for UL subframe 3.

In accordance with this example, one or more virtual subframes, i.e., Xas shown in Table 6, also referred to as an offset, may be added intothe second DL association subset, so as to form a new second DLassociation subset. The one or more virtual subframes are only used forassigning PUCCH resource indices, but not for real PDSCH transmissions.For example, the one or more virtual subframes may be treated as SF n-7in this example. In this case, the above Example 1 and Example 2 may beapplied to the new second DL association subset.

TABLE 6 Example DL association set index K: {k₀ ^((q)), . . . , k_(M)_(q)−1^((q))} for TDD when UL reference TDD configuration isconfiguration 6 and DL reference TDD configuration is 1 UL-DL Subframe nConfiguration 0 1 2 3 4 5 6 7 8 9 6 — — 7 7 5 — — 7 7 — 1 — — 7, 6 X, 4— — — 7, 6 X, 4 —

Second Embodiment

As the second embodiment of the invention, a method used in a UE forreporting HARQ ACK/NACK for PDSCH in dynamic TDD configurations isproposed.

In the method, referring to FIG. 9 which shows a flowchart of the method900, a plurality of PDSCHs are received in DL subframes associated withan UL subframe and indicated by a DL reference TDD configuration (Step910). For each of the received PDSCHs, HARQ ACK/NACK is reported by atleast partially using PUCCH resources indicated by DCI and/or RRCsignaling (Step 920).

Optionally, the method 900 may also include the following steps.Firstly, the DL subframes are divided into a first subset of DLsubframes and a second subset of DL subframes (Step 930). The firstsubset of DL subframes is according to this example also indicated by anUL reference TDD configuration. Then, a set of PUCCH resource indicesare assigned based on resources used in transmission of PDCCHscorresponding to the PDSCHs received in the DL subframes of the firstsubset of DL subframes (Step 940). Thereafter, for each of the PDSCHsreceived in the DL subframes of the first subset of DL subframes, HARQACK/NACK is reported by using PUCCH resources in an order of theassigned set of PUCCH resource indices (Step 950). Finally, for each ofthe PDSCHs received in the DL subframes of the second subset of DLsubframes, HARQ ACK/NACK is reported by using PUCCH resources indicatedby DCI and/or RRC signaling (Step 960).

In some embodiments of the present disclosure, the second subset of DLsubframes may comprise all the DL subframes indicated by the DLreference TDD configuration other than DL subframes of the first subsetof DL subframes.

In some embodiments of the present disclosure, the first subset of DLsubframes may comprise one or more virtual subframes that are added bythe UE, and the one or more virtual subframes may be used only forassigning PUCCH resource indices, but not for real PDSCH transmissions.

For DL subframes in the first subset of DL subframes, correspondingPUCCH resources may be stacked according to the UL reference TDDconfiguration and implicitly determined by the first CCE index used fortransmission of the corresponding PDCCH.

For DL subframes in the second subset of DL subframes, correspondingPUCCH resource may explicitly signaled, e.g. by DCI and/or RRCsignaling.

For example, for DL subframes in the first subset of DL subframes, thecorresponding PUCCH resource may be determined by the above equation(1). For the DL subframes in the second subset of DL subframes, the UEmay use PUCCH resource index n_(PUCCH,i) ⁽¹⁾, where the value ofn_(PUCCH,i) ⁽¹⁾ is determined according to higher layer configurationand/or the predefined mapping rules as shown in Table 7.

One field in the DCI format of the corresponding PDCCH may be used todetermine the PUCCH resource values from one of the four resource valuesconfigured by higher layers, with the mapping defined in Table 7.

As a non-limiting example, the field in DCI to indicate PUCCH resourcevalues may be some existing field, e.g. the Transport Power Control(TPC) field. When the existing field is reused, if the DCI is granted orreceived in the second subset of DL subframes, this field is interpretedas PUCCH resource; and if the DCI is granted or received in the firstsubset of DL subframes, the field is interpreted according to itsoriginal definition.

TABLE 7 PUCCH resource value for HARQ-ACK resource for PUCCH Value of“command for PUCCH” n_(PUCCH,i) ⁽¹⁾ ‘00’ The 1^(st) PUCCH resource indexconfigured by the higher layers ‘01’ The 2^(nd) PUCCH resource indexconfigured by the higher layers ‘10’ The 3^(rd) PUCCH resource indexconfigured by the higher layers ‘11’ The 4^(th) PUCCH resource indexconfigured by the higher layers

As another non-limiting example, new bits may be added to indicate PUCCHresource values. The new field may be added only on the DCI granted orreceived in the second subset of DL subframes, and the new field may notbe available in the DCI granted or received in the first subset of DLsubframes.

As another non-limiting example, if a new field is added to indicatePUCCH resource values, the new field may be interpreted as PUCCHresource for DCI granted or received in the second subset of DLsubframes, whereas the field may be used for another purpose than PUCCHresource value indication for DCI granted or received in the firstsubset of DL subframes.

As a non-limiting example, for all DL transmissions, PUCCH resources maybe explicitly signaled by dynamic grant, e.g. DCI, and/or RRC signaling.

In this example, the UE may use PUCCH resource index n_(PUCCH,i) ⁽¹⁾,where the value of n_(PUCCH,i) ⁽¹⁾, is determined according to higherlayer configuration and/or a predefined rule, e.g., a predefined tableas shown in Table 7.

One field in the DCI format of the corresponding PDCCH may be used todetermine the PUCCH resource values from one of the four resource valuesconfigured by higher layers, with the mapping defined in Table 7.

Third Embodiment

As the third embodiment of the invention, a method used in a UE forreporting HARQ ACK/NACK for PDSCH in dynamic TDD configurations isproposed.

In the method, referring to FIG. 10 which shows a flowchart of themethod 1000, a plurality of PDSCHs are received in DL subframesassociated with an UL subframe and indicated by a DL reference TDDconfiguration (Step 1010). For each of the received PDSCHs, a PUCCHresource is determined based on resources used in transmission ofPhysical Downlink Control Channels (PDCCHs) corresponding to the PDSCHsreceived in the corresponding DL subframe (e.g., the sequence number ofthe first CCE used for transmission of PDCCHs corresponding to thereceived PDSCH in the corresponding DL subframe) and a start position ofthe PUCCH resource corresponding to the DL subframe (Step 1020); andthen HARQ ACK/NACK is reported by using the determined PUCCH resource(Step 1030).

If there is no legacy UEs in the system and all the UEs are new releaseUEs, i.e. Dynamic-TDD-enabled UEs, we can have different offsets per DLsubframe. In this case, an index of PUCCH resource n_(PUCCH,i) ⁽¹⁾ insubframe i may be determined as follows:

n _(PUCCH,i) ^((1) =n) _(CCE,i) +N _(UE-PUCCH) ^((i,))

where n_(CCE,i) is the number of the first CCE used for transmission ofthe corresponding PDCCH in subframe n−k_(i), N_(UE-PUCCH) ^((i)) is theoffset corresponding to the DL subframe n−k_(i), and N_(UE-PUCCH) ^((i))is configured by higher layers.

In the following, an example will be explained in detail by assumingthat the UL reference TDD configuration is TDD configuration 0, and theDL reference TDD configuration is TDD configuration 2. In theseexamples, the subframes #3, #4, #8 and #9 are flexible subframes thatcan be allocated as UL and DL subframes.

EXAMPLE 1 TDD Configuration 0 (UL), TDD Configuration 2 (DL)

In this example, for UL subframe 2, the first DL association subset is{SF n-6}, and the second DL association subset is {SF n-8, SF n-7, SFn-4}, as shown in Table 5.

FIG. 11 illustrates an example of how the PUCCH HARQ-ACK resources maybe stacked. As shown in FIG. 11, PUCCH HARQ-ACK resources for all CCEindices of each DL subframe, i.e., all three one-third CCEs of the DLsubframe, are stacked continuously, and each DL subframe corresponds toan offset.

In this example, a start position of a PUCCH resource corresponding tothe DL subframe may be separately configured using related informationinformed by broadcasting, RRC signaling, MAC CE, etc.

Fourth Embodiment

As the fourth embodiment of the invention, a method used in a UE forreporting HARQ ACK/NACK for PDSCH in dynamic TDD configurations isproposed.

In the method, referring to FIG. 12 which shows a flowchart of themethod 1200, a plurality of PDSCHs are received in DL subframesassociated with an UL subframe and indicated by a DL reference TDDconfiguration (Step 1210). A DL subframe of the DL subframes is selectedto be a first DL subframe (Step 1220), so that the sequence number ofthe selected DL subframe is the same as that of a first DL subframe ofDL subframes associated with the UL subframe but indicated by an ULreference TDD configuration. PUCCH resource indices are assigned basedon resources used in transmission of PDCCHs corresponding to the PDSCHsreceived in the DL subframes associated with the UL subframe andindicated by the DL reference TDD configuration (Step 1230). The PUCCHresource indices are assigned in an order starting from the selectedfirst DL subframe of the DL subframes associated with the UL subframeand indicated by the DL reference TDD configuration. For each of thereceived PDSCHs, HARQ ACK/NACK is reported by using PUCCH resources inthe order of the assigned PUCCH resource indices (Step 1240).

In this embodiment, the same resource allocation method is used as forthe legacy user or UE, but a different order is used for the DLassociation set for the specific subframe. The new permutation may beindicated by a new look-up table or by rules specified in the standard.

In some examples, the order of the values in the DL association set maybe rearranged such that the first values in the DL association set of DLreference TDD configuration match the values in the DL association setfor the UL reference/broadcasted TDD configuration for the samesubframe, where possible.

In some examples, also other values in the DL association set may berearranged in order to match the likelihood of the subframes to be usedfor DL transmissions. For example, subframes related to DL in both theUL and the DL reference TDD configuration may be mapped first. Subframeshaving different directions in the two configurations could then bemapped in order counting from the UL to DL switching-point in the ULconfiguration.

Table 8 shows an example DL association set index according tot hefourth embodiment.

TABLE 8 Example DL association set index K: {k₀ ^((q)), . . . , k_(M)_(q)−1^((q))} for TDD when UL reference TDD configuration isconfiguration 0 and DL reference TDD configuration is 2 UL-DL Configura-Subframe n tion 0 1 2 3 4 5 6 7 8 9 0 — — 6 — 4 — — 6 — 4 2 — — 6, 7, 8,4 — — — — 6, 7, 8, 4 — —

As shown in Table 8, DL subframes in the original second DL associationset for UL subframe SF n-2, i.e., {SF n-8, SF n-7, SF n-4, SF n-6}, maybe rearranged as {SF n-6, SF n-7, SF n-8, SF n-4}, so that PUCCHresources for responding to PDSCHs transmitted in the subframe SF n-6may be stacked firstly. This may be illustrated in FIG. 13.

FIG. 14 is a schematic block diagram of a UE 1400 according to someembodiments of the present disclosure.

As shown, UE 1400 includes a receiver 1410, a transmitter 1420, a memory1430 and a processor 1440. The memory 1430 is configured to store TDDconfigurations, e.g., TDD configurations 0-6. The processor 1440 isconfigured to control, e.g., according to instructions stored in thememory 1430, the receiver 1410 to receive a plurality of PDSCHs in DLsubframes associated with an UL subframe and indicated by a DL referenceTDD configuration. The processor 1440 is further configured to dividethe DL subframes into a first subset of DL subframes and a second subsetof DL subframes. The first subset of DL subframes is also indicated byan UL reference TDD configuration. The processor 1440 is also configuredto assign a first set of PUCCH resource indices based on resources usedin transmission of PDCCHs corresponding to the PDSCHs received in the DLsubframes of the first subset of DL subframes. Moreover, the processor1440 is configured to assign a second set of PUCCH resource indicesbased on resources used in transmission of PDCCHs corresponding to thePDSCHs received in the DL subframes of the second subset of DLsubframes. The processor 1440 is also configured to control, e.g.,according to instructions stored in the memory 1430, the transmitter1420 to, for each of the received PDSCHs, report HARQ ACK/NACK by usingPUCCH resources in an order of the assigned first set of PUCCH resourceindices for PDSCHs received in the DL subframes of the first subset ofDL subframes and in an order of the assigned second set of PUCCHresource indices for PDSCHs received in the DL subframes of the secondsubset of DL subframes.

For example, the processor 1440 may be configured to assign the firstset of PUCCH resource indices and the second set of PUCCH resourceindices based on the following formula:

n _(PUCCH,i) ⁽¹⁾=(M _(q) −i−1)·N _(c) i·N _(c+1) +n _(CCE,i) +N _(PUCCH)^((q)).

wherein n_(PUCCH,i) ⁽¹⁾ is a PUCCH resource index determined based onresources used in transmission of PDCCHs corresponding to the PDSCHsreceived in the DL subframe that is the i^(th) element of the q^(th)subset, M_(q) is the total number of DL subframes in the q^(th) subset,0≦i<M_(q), c is selected from {0,1,2,3} such thatN_(c)≦n_(CCE,i)<N_(c+1), N_(c)=max {0,└[N_(RB) ^(DL)·(N_(sc)^(RB)·c−4)/36┘]} where N_(RB) ^(DL) is the number of physical resourceblocks, PRBs, in each downlink subframe and where N_(sc) ^(RB) is thenumber of subcarriers in each physical resource block, n_(CCE,i) is thesequence number of the first Control Channel Element, CCE, used fortransmission of the corresponding PDCCH in subframe n−k_(i) ^((q)),k_(i) ^((q )) (q=0,1) is the i^(th) element of the q^(th) subset, nindicates the UL subframe associated with the DL subframes where theplurality of PDSCHs are received, N_(PUCCH) ^((q)) (q=0,1) is an offsetfor q^(th) subset, wherein q=0 corresponds to one of the first andsecond subsets of DL subframes and q=1 corresponds to the other one ofthe first and second subsets of DL subframes.

As above, there may be an offset between the first set of PUCCH resourceindices and the second set of PUCCH resource indices.

As above, the offset may be configured by higher layers or predefined.

As above, the second subset of DL subframes may comprise all the DLsubframes indicated by the DL reference TDD configuration other than DLsubframes of the first subset of DL subframes.

The processor 1440 may further be configured to add one or more virtualsubframes to the first subset of DL subframes. The one or more virtualsubframes may be used for assigning PUCCH resource indices, but not forreal PDSCH transmissions.

FIG. 15 is a schematic block diagram of a UE 1500 according to someembodiments of the present disclosure.

As shown, UE 1500 includes a receiver 1510, a transmitter 1520, a memory1530 and a processor 1540. The memory 1530 is configured to store TDDconfigurations, e.g., TDD configurations 0-6. The processor 1540 isconfigured to control, e.g., according to instructions stored in thememory 1530, the receiver 1510 to receive a plurality of PDSCHs in DLsubframes associated with an UL subframe and indicated by a DL referenceTDD configuration. The processor 1540 is also configured to control,e.g., according to instructions stored in the memory 1530, thetransmitter 1520 to, for each of the received PDSCHs, report HARQACK/NACK by at least partially using PUCCH resources indicated by DCIand/or RRC signaling.

Alternatively or additionally, the processor 1540 may be configured todivide the DL subframes into a first subset of DL subframes and a secondsubset of DL subframes. The first subset of DL subframes is according tothis example also indicated by an UL reference TDD configuration. Theprocessor 1540 may further be configured to assign a set of PUCCHresource indices based on resources used in transmission of PDCCHscorresponding to the PDSCHs received in the DL subframes of the firstsubset of DL subframes. In this case, the processor 1540 may also beconfigured to control, e.g., according to instructions stored in thememory 1530, the transmitter 1520 to, for each of the PDSCHs received inthe DL subframes of the first subset of DL subframes, report HARQACK/NACK by using PUCCH resources in an order of the assigned set ofPUCCH resource indices. Finally, the processor 1540 may be configured tocontrol, e.g., according to instructions stored in the memory 1530, thetransmitter 1520 to, for each of the PDSCHs received in the DL subframesof the second subset of DL subframes, report HARQ ACK/NACK by usingPUCCH resources indicated by DCI and/or RRC signaling.

As above, the second subset of DL subframes may comprise all the DLsubframes indicated by the DL reference TDD configuration other than DLsubframes of the first subset of DL subframes.

The processor 1540 may further be configured to add one or more virtualsubframes to the first subset of DL subframes. The one or more virtualsubframes may be used for assigning PUCCH resource indices, but not forreal PDSCH transmissions.

FIG. 16 is a schematic block diagram of a UE 1600 according to someembodiments of the present disclosure.

As shown, UE 1600 includes a receiver 1610, a transmitter 1620, a memory1630 and a processor 1640. The memory 1630 is configured to store TDDconfigurations, e.g., TDD configurations 0-6. The processor 1640 isconfigured to control, e.g., according to instructions stored in thememory 1630, the receiver 1610 to receive a plurality of PDSCHs in DLsubframes associated with an UL subframe and indicated by a DL referenceTDD configuration. The processor 1640 is further configured todetermine, for each of the received PDSCHs, a PUCCH resource based onresources used in transmission of Physical Downlink Control Channels(PDCCHs) corresponding to the PDSCHs received in the corresponding DLsubframe (e.g., the sequence number of the first CCE used fortransmission of PDCCHs corresponding to the received PDSCH in thecorresponding DL subframe) and a start position of the PUCCH resourcecorresponding to the DL subframe. The processor 1640 is also configuredto control, e.g., according to instructions stored in the memory 1630,the transmitter 1620 to, for each of the received PDSCHs, report HARQACK/NACK by using the determined PUCCH resource.

As above, the start position may be configured by higher layers orpredefined.

As above, the start position may be configured using related informationinformed by broadcasting, RRC signaling, or MAC CE.

FIG. 17 is a schematic block diagram of a UE 1700 according to someembodiments of the present disclosure.

As shown, UE 1700 includes a receiver 1710, a transmitter 1720, a memory1730 and a processor 1740. The memory 1730 is configured to store TDDconfigurations, e.g., TDD configurations 0-6. The processor 1740 isconfigured to control, e.g., according to instructions stored in thememory 1730, the receiver 1710 to receive a plurality of PDSCHs in DLsubframes associated with an UL subframe and indicated by a DL referenceTDD configuration. The processor 1740 is further configured to select aDL subframe of the DL subframes to be a first DL subframe. The sequencenumber of the selected DL subframe is the same as that of a first DLsubframe of DL subframes associated with the UL subframe but indicatedby an UL reference TDD configuration. The processor 1740 is furtherconfigured to assign PUCCH resource indices based on resources used intransmission of PDCCHs corresponding to the PDSCHs received in the DLsubframes associated with the UL subframe and indicated by the DLreference TDD configuration. The PUCCH resource indices are assigned inan order starting from the selected first DL subframe of the DLsubframes associated with the UL subframe and indicated by the DLreference TDD configuration. The processor 1740 is further configured tocontrol, e.g., according to instructions stored in the memory 1730, thetransmitter 1720 to, for each of the received PDSCHs, report HARQACK/NACK by using PUCCH resources in the order of the assigned PUCCHresource indices.

As described in the above embodiments, legacy UEs as well asDynamic-TDD-enabled UEs can be supported and the PUCCH HARQ-ACK resourceconflict problem caused by dynamic TDD configuration is solved, whileefficiently compressing PUCCH HARQ-ACK resource to improve the resourceutilization efficiency.

Fifth Embodiment

As the fifth embodiment of the invention, a method used in a BS forreceiving HARQ ACK/NACK for PDSCH in dynamic TDD configurations isproposed.

In the method, referring to FIG. 18 which shows a flowchart of themethod 1800, a plurality of PDSCHs are transmitted in DL subframesassociated with an UL subframe and indicated by a DL reference TDDconfiguration (Step 1810). The DL subframes are divided into a firstsubset of DL subframes and a second subset of DL subframes (Step 1820).The first subset of DL subframes is also indicated by an UL referenceTDD configuration. Hereinafter, DL subframes associated with the ULsubframe and indicated by a UL reference TDD configuration may bereferred to as the first DL association subframes of the UL subframe,and DL subframes associated with a UL subframe and indicated by a DLreference TDD configuration may be referred to as the second DLassociation subframes of the UL subframe. Thus, the first subset of DLsubframes and the second subset of DL subframes may be referred to asthe first DL association subset and the second DL association subset,respectively. Then, a first set of PUCCH resource indices are assignedbased on resources used in transmission of PDCCHs corresponding to thePDSCHs transmitted in the DL subframes of the first subset of DLsubframes (Step 1830), and a second set of PUCCH resource indices areassigned based on resources used in transmission of PDCCHs correspondingto the PDSCHs transmitted in the DL subframes of the second subset of DLsubframes (Step 1840). Thereafter, for each of the transmitted PDSCHs,HARQ ACK/NACK is received by using PUCCH resources in an order of theassigned first set of PUCCH resource indices for PDSCHs transmitted inthe DL subframes of the first subset of DL subframes and in an order ofthe assigned second set of PUCCH resource indices for PDSCHs transmittedin the DL subframes of the second subset of DL subframes (Step 1850).

In the present disclosure, there is an offset between the first set ofPUCCH resource indices and the second set of PUCCH resource indices. Theoffset herein may be configured by higher layers or predefined. Forexample, the offset may be notified by the eNB via RRC signaling or MACCE.

In the present disclosure, the first set of PUCCH resource indices andthe second set of PUCCH resource indices may have different startpositions, which may be referred to as start positions of PUCCHresources.

In some embodiments of the present disclosure, the steps of 1830 and1840 may be performed based on the following formula:

n _(PUCCH,i) ⁽¹⁾=(M _(q) −i−1)·N_(c) ·N _(c+1) +n _(CCE,i) +N _(PUCCH)^((q)),   (2)

wherein n_(PUCCH,i) ⁽¹⁾ is a PUCCH resource index determined based onresources used in transmission of PDCCHs corresponding to the PDSCHsreceived in the DL subframe that is the ^(i)th element of the q^(th)subset, M_(q) is the total number of DL subframes in the q^(th) subset,0≦i<M_(q), c is selected from {0,1,2,3} such thatN_(c)≦n_(CCE,i)<N_(c+1), N_(c)=max {0,└[N_(RB) ^(DL)·(N_(sc)^(RB)·c−4)]/36┘} where N_(RB) ^(DL) is the number of physical resourceblocks, PRBs, in each downlink subframe and where N_(sc) ^(RB) is thenumber of subcarriers in each physical resource block, n_(CCE,i) is thesequence number of the first Control Channel Element, CCE, used fortransmission of the corresponding PDCCH in subframe n−k_(i) ^((q)),k_(i) ^((q))(q=0,1) is the i^(th) element of the q^(th) subset, nindicates the UL subframe associated with the DL subframes where theplurality of PDSCHs are received, N_(PUCCH) ^((q))(q=0,1) is an offsetfor q^(th) subset, wherein q=0 corresponds to one of the first andsecond subsets of DL subframes and q=1 corresponds to the other one ofthe first and second subsets of DL subframes. The offset may beconfigured by higher layers.

In some embodiments of the present disclosure, the second subset of DLsubframes may comprise all the DL subframes indicated by the DLreference TDD configuration other than DL subframes of the first subsetof DL subframes.

In some embodiments of the present disclosure, the first subset of DLsubframes may comprise one or more virtual subframes that are added bythe BS, and the one or more virtual subframes may be used only forassigning PUCCH resource indices, but not for real PDSCH transmissions.

In the following, some examples will be explained in detail by assumingthat the UL reference TDD configuration is TDD configuration 0 or TDDconfiguration 1 or TDD configuration 6, and the DL reference TDDconfiguration is TDD configuration 1 or TDD configuration 2. In theseexamples, the subframes #3, #4, #8 and #9 are flexible subframes thatcan be allocated as UL and DL subframes.

EXAMPLE 1 TDD Configuration 1 (UL), TDD Configuration 2 (DL)

In this example, for UL subframe 2, the first DL association subset canbe {7, 6}, and the second DL association subset can be {8,4}. An exampleDL association subset is shown in Table 9.

TABLE 9 Example DL association set index K: {k₀ ^((q)), . . . , k_(M)_(q)−1^((q))} for TDD when UL reference TDD configuration isconfiguration 1 and DL reference TDD configuration is 2. UL-DL Subframen Configuration 0 1 2 3 4 5 6 7 8 9 1 — — {7, 6} — 4 — — {7, 6} — 4 2 —— Subset 1: {7, 6} — — — — Subset 1: {7, 6} — — Subset 2: {8, 4} Subset2: {8, 4}FIG. 19 illustrates how the PUCCH HARQ-ACK resource can be stacked. Asshown in FIG. 19, subframes SF n-6 and SF n-7 not only belong toConfiguration 2 but also belong to configuration 1. Correspondingly, asshown in the left part of FIG. 19, their corresponding PUCCH HARQ-ACKresources may be stacked firstly. That is, PUCCH resource indices forPDSCHs transmitted in the subframes SF n-6 and SF n-7 may be smallerthan those for PDSCHs transmitted in the remaining DL subframes. FIG. 19is just an illustrative example, and the present disclosure is notlimited to this example. For example, PUCCH resource indices for PDSCHstransmitted in the subframes SF n-6 and SF n-7 may be larger than thosefor PDSCHs transmitted in the remaining DL subframes. PUCCH HARQ-ACKresources corresponding to other DL association subframes, may bestacked in a similar way but with a separate offset (i.e., N_(PUCCH)⁽¹⁾).

EXAMPLE 2 TDD Configuration 0 (UL), TDD Configuration 2 (DL)

In this example, for UL subframe 2, the first DL association subset is{6}, and the second DL association subset is {8,7,4}. An example DLassociation subset is shown in Table 10.

TABLE 10 Example DL association set index K: {k₀ ^((q)), . . . , k_(M)_(q)−1^((q))} for TDD when UL reference TDD configuration isconfiguration 0 and DL reference TDD configuration is 2 UL-DL Subframe nConfiguration 0 1 2 3 4 5 6 7 8 9 0 — — 6 — 4 — — 6 — 4 2 — — Subset 1:{6} — — — — Subset 1: {6} — — Subset 2: {8, 7, 4} Subset 2: {8, 7, 4}FIG. 20 illustrates how the PUCCH HARQ-ACK resource can be stacked. Asshown in FIG. 20, subframe SF n-6 not only belongs to Configuration 2,but also belongs to Configuration 0. Correspondingly, as shown in theleft part of FIG. 20, their corresponding PUCCH HARQ-ACK resources maybe stacked firstly. That is, PUCCH resource indices for PDSCHstransmitted in the subframe SF n-6 may be smaller than those for PDSCHstransmitted in the remaining DL subframes. FIG. 20 is just anillustrative example, and the present disclosure is not limited to thisexample. For example, PUCCH resource indices for PDSCHs transmitted inthe subframe SF n-6 may be larger than those for PDSCHs transmitted inthe remaining DL subframes. PUCCH HARQ-ACK resources corresponding toother DL association subframes may be stacked in a similar way but witha separate offset (i.e., N_(PUCCH) ⁽¹⁾).

EXAMPLE 3 TDD Configuration 6 (UL), TDD Configuration 1 (DL)

In this example, for UL subframe 3, the first DL association subset is{7}, and the second DL association subset is {4}. An example DLassociation subset is shown in Table 11. As shown in Table 11, thesecond DL association subset for UL subframe 3 contains no DL subframehaving the same sequence number as that of any DL subframe in the firstDL association subset for UL subframe 3.

In accordance with this example, one or more virtual subframes, i.e., Xas shown in Table 11, also referred to as an offset, may be added intothe second DL association subset, so as to form a new second DLassociation subset. The one or more virtual subframes are only used forassigning the second set of PUCCH resource indices, but not for realPDSCH transmissions. For example, the one or more virtual subframes maybe treated as SF n-7 in this example. In this case, the above Example 1and Example 2 may be applied to the new second DL association subset.

TABLE 11 Example DL association set index K: {k₀ ^((q)), . . . , k_(M)_(q)−1^((q))} for TDD when UL reference TDD configuration isconfiguration 6 and DL reference TDD configuration is 1 UL-DL Subframe nConfiguration 0 1 2 3 4 5 6 7 8 9 6 — — 7 7 5 — — 7 7 — 1 — — 7, 6 X, 4— — — 7, 6 X, 4 —

Sixth Embodiment

As the sixth embodiment of the invention, a method used in a BS forreceiving HARQ ACK/NACK for PDSCH in dynamic TDD configurations isproposed.

In the method, referring to FIG. 21 which shows a flowchart of themethod 2100, a plurality of PDSCHs are transmitted in DL subframesassociated with an UL subframe and indicated by a DL reference TDDconfiguration (Step 2110 ). For each of the transmitted PDSCHs, HARQACK/NACK is received by at least partially using PUCCH resourcesindicated by DCI and/or RRC signaling (Step 2120).

Optionally, the method 2100 may also include the following steps.Firstly, the DL subframes are divided into a first subset of DLsubframes and a second subset of DL subframes (Step 2130). The firstsubset of DL subframes is also indicated by an UL reference TDDconfiguration. Then, a set of PUCCH resource indices are assigned basedon resources used in transmission of PDCCHs corresponding to the PDSCHstransmitted in the DL subframes of the first subset of DL subframes(Step 2140). Thereafter, for each of the PDSCHs transmitted in the DLsubframes of the first subset of DL subframes, HARQ ACK/NACK is receivedby using PUCCH resources in an order of the assigned set of PUCCHresource indices (Step 2150). Finally, for each of the PDSCHstransmitted in the DL subframes of the second subset of DL subframes,HARQ ACK/NACK is received by using PUCCH resources indicated by DCIand/or RRC signaling (Step 2160).

In some embodiments of the present disclosure, the second subset of DLsubframes may comprise all the DL subframes indicated by the DLreference TDD configuration other than DL subframes of the first subsetof DL subframes.

In some embodiments of the present disclosure, the first subset of DLsubframes may comprise one or more virtual subframes that are added bythe BS, and the one or more virtual subframes may be usd only forassigning PUCCH resource indices, but not for real PDSCH transmissions.

For DL subframes in the first subset of DL subframes, correspondingPUCCH resources may be stacked according to the UL reference TDDconfiguration and implicitly determined by the first CCE index used fortransmission of the corresponding PDCCH.

For DL subframes in the second subset of DL subframes, correspondingPUCCH resource may explicitly signaled, e.g. by DCI and/or RRCsignaling.

For example, for DL subframes in the first subset of DL subframes, thecorresponding PUCCH resource may be determined by the above equation(2). For the DL subframes in the second subset of DL subframes, the BSmay use PUCCH resource index n_(PUCCH,i) ⁽¹⁾, where the value ofn_(PUCCH,i) ⁽¹⁾) , is determined according to higher layer configurationand/or the predefined mapping rules as shown in Table 12.

One field in the DCI format of the corresponding PDCCH may be used todetermine the PUCCH resource values from one of the four resource valuesconfigured by higher layers, with the mapping defined in Table 12.

As a non-limiting example, the field in DCI to indicate PUCCH resourcevalues may be some existing field, e.g. the Transport Power Control(TPC) field. When the existing field is reused, if the DCI is granted ortransmitted in the second subset of DL subframes, this field isinterpreted as PUCCH resource; and if the DCI is granted or transmittedin the first subset of DL subframes, the field is interpreted accordingto its original definition.

TABLE 12 PUCCH resource value for HARQ-ACK resource for PUCCH Value of“command for PUCCH” n_(PUCCH,i) ⁽¹⁾ ‘00’ The 1^(st) PUCCH resource indexconfigured by the higher layers ‘01’ The 2^(nd) PUCCH resource indexconfigured by the higher layers ‘10’ The 3^(rd) PUCCH resource indexconfigured by the higher layers ‘11’ The 4^(th) PUCCH resource indexconfigured by the higher layersAs another non-limiting example, new bits may be added to indicate PUCCHresource values. The new field may be added only on the DCI granted ortransmitted in the second subset of DL subframes, and the new field maynot be available in the DCI granted or transmitted in the first subsetof DL subframes.

As another non-limiting example, if a new field is added to indicatePUCCH resource values, the new field may be interpreted as PUCCHresource for DCI granted or transmitted in the second subset of DLsubframes; whereas the field may be used for another purpose than PUCCHresource value indication for DCI granted or transmitted in the firstsubset of DL subframes.

As a non-limiting example, for all DL transmissions, PUCCH resources maybe explicitly signaled by dynamic grant, e.g. DCI, and/or RRC signaling.

In this example, the BS may use PUCCH resource index n_(PUCCH,i) ⁽¹⁾where the value of n_(PUCCH,i) ⁽¹⁾) is determined according to higherlayer configuration and/or a predefined rule, e.g., a predefined tableas shown in Table 12.

One field in the DCI format of the corresponding PDCCH may be used todetermine the PUCCH resource values from one of the four resource valuesconfigured by higher layers, with the mapping defined in Table 12.

Seventh Embodiment

As the seventh embodiment of the invention, a method used in a BS forreceiving HARQ ACK/NACK for PDSCH in dynamic TDD configurations isproposed.

In the method, referring to FIG. 22 which shows a flowchart of themethod 2200, a plurality of PDSCHs are transmitted in DL subframesassociated with an UL subframe and indicated by a DL reference TDDconfiguration (Step 2210). For each of the transmitted PDSCHs, a PUCCHresource is determined based on resources used in transmission ofPhysical Downlink Control Channels (PDCCHs) corresponding to the PDSCHstransmitted in the corresponding DL subframe (e.g., the sequence numberof the first CCE used for transmission of PDCCHs corresponding to thetransmitted PDSCH in the corresponding DL subframe) and a start positionof the PUCCH resource corresponding to the DL subframe (Step 2220); andthen HARQ ACK/NACK is received by using the determined PUCCH resource(Step 2230).

If there is no legacy UEs in the system and all the UEs are new releaseUEs, i. e. Dynamic-TDD-enabled UEs, we can have different offsets per DLsubframe. In this case, an index of PUCCH resource n_(PUCCH,i) ⁽¹⁾ insubframe i may be determined as follows:

n _(PUCCH,i) ⁽¹⁾ =n _(CCE,i) +N _(UE-PUCCH) ^((i,))

where n_(CCE,i) is the number of the first CCE used for transmission ofthe corresponding PDCCH in subframe n−k_(i), N_(UE-PUCCH) ^((i)) is theoffset corresponding to the DL subframe n−_(i), and N_(UE-PUCCH) ^((i))is configured by higher layers.

In the following, an example will be explained in detail by assumingthat the UL reference TDD configuration is TDD configuration 0, and theDL reference TDD configuration is TDD configuration 2. In theseexamples, the subframes #3, #4, #8 and #9 are flexible subframes thatcan be allocated as UL and DL subframes.

EXAMPLE 1 TDD Configuration 0 (UL), TDD Configuration 2 (DL)

In this example, for UL subframe 2, the first DL association subset is{SF n-6}, and the second DL association subset is {SF n-8, SF n-7, SFn-4}, as shown in Table 9.

FIG. 23 illustrates an example of how the PUCCH HARQ-ACK resources maybe stacked. As shown in FIG. 23, PUCCH HARQ-ACK resources for all CCEindices of each DL subframe, i.e., all three one-third CCEs of the DLsubframe, are stacked continuously, and each DL subframe corresponds toan offset.

In this example, a start position of a PUCCH resource corresponding tothe DL subframe may be separately configured using related informationinformed by broadcasting, RRC signaling, MAC CE, etc.

Eighth Embodiment

As the eighth embodiment of the invention, a method used in a BS forreceiving HARQ ACK/NACK for PDSCH in dynamic TDD configurations isproposed.

In the method, referring to FIG. 24 which shows a flowchart of themethod 2400, a plurality of PDSCHs are transmitted in DL subframesassociated with an UL subframe and indicated by a DL reference TDDconfiguration (Step 2410). A DL subframe of the DL subframes is selectedto be a first DL subframe (Step 2420), so that the sequence number ofthe selected DL subframe is the same as that of a first DL subframe ofDL subframes associated with the UL subframe but indicated by an ULreference TDD configuration. PUCCH resource indices are assigned basedon resources used in transmission of PDCCHs corresponding to the PDSCHstransmitted in the DL subframes associated with the UL subframe andindicated by the DL reference TDD configuration (Step 2430). The PUCCHresource indices are assigned in an order starting from the selectedfirst DL subframe of the DL subframes associated with the UL subframeand indicated by the DL reference TDD configuration. For each of thetransmitted PDSCHs, HARQ ACK/NACK is received by using PUCCH resourcesin the order of the assigned PUCCH resource indices (Step 2440).

In this embodiment, the same resource allocation method is used as forthe legacy user or UE, but a different order is used for the DLassociation set for the specific subframe. The new permutation may beindicated by a new look-up table or by rules specified in the standard.

In some examples, the order of the values in the DL association set maybe rearranged such that the first values in the DL association set of DLreference TDD configuration match the values in the DL association setfor the UL reference/broadcasted TDD configuration for the samesubframe, where possible.

In some examples, also other values in the DL association set may berearranged in order to match the likelihood of the subframes to be usedfor DL transmissions. For example, subframes related to DL in both theUL and the DL reference TDD configuration may be mapped first. Subframeshaving different directions in the two configurations could then bemapped in order counting from the UL to DL switching-point in the ULconfiguration.

Table 13 shows an example DL association set index according to theeighth embodiment.

TABLE 13 Example DL association set index K: {k₀ ^((q)), . . . , k_(M)_(q)−1^((q))} for TDD when UL reference TDD configuration isconfiguration 0 and DL reference TDD configuration is 2. UL-DLConfigura- Subframe n tion 0 1 2 3 4 5 6 7 8 9 0 — — 6 — 4 — — 6 — 4 2 —— 6, 7, 8, 4 — — — — 6, 7, 8, 4 — —

As shown in Table 13, DL subframes in the original second DL associationset for UL subframe SF n-2, i.e., {SF n-8, SF n-7, SF n-4, SF n-6}, maybe rearranged as {SF n-6, SF n-7, SF n-8, SF n-4}, so that PUCCHresources for UE responses to PDSCHs transmitted in the subframe SF n-6may be stacked firstly. This may be illustrated in FIG. 25.

FIG. 26 is a schematic block diagram of a BS 2600 according to someembodiments of the present disclosure.

As shown, BS 2600 includes a receiver 2610, a transmitter 2620, a memory2630 and a processor 2640. The memory 2630 is configured to store TDDconfigurations, e.g., TDD configurations 0-6. The processor 2640 isconfigured to control, e.g., according to instructions stored in thememory 2630, the transmitter 2620 to transmit a plurality of PDSCHs inDL subframes associated with an UL subframe and indicated by a DLreference TDD configuration. The processor 2640 is further configured todivide the DL subframes into a first subset of DL subframes and a secondsubset of DL subframes. The first subset of DL subframes is alsoindicated by an UL reference TDD configuration. The processor 2640 isalso configured to assign a first set of PUCCH resource indices based onresources used in transmission of PDCCHs corresponding to the PDSCHstransmitted in the DL subframes of the first subset of DL subframes.Moreover, the processor 2640 is configured to assign a second set ofPUCCH resource indices based on resources used in transmission of PDCCHscorresponding to the PDSCHs transmitted in the DL subframes of thesecond subset of DL subframes. The processor 2640 is also configured tocontrol, e.g., according to instructions stored in the memory 2630, thereceiver 2610 to, for each of the transmitted PDSCHs, receive HARQACK/NACK on PUCCH resources in an order of the assigned first set ofPUCCH resource indices for PDSCHs transmitted in the DL subframes of thefirst subset of DL subframes and in an order of the assigned second setof PUCCH resource indices for PDSCHs transmitted in the DL subframes ofthe second subset of DL subframes.

For example, the processor 2640 may be configured to assign the firstset of PUCCH resource indices and the second set of PUCCH resourceindices based on the following formula:

n _(PUCCH,i) ⁽¹⁾=(M _(q) −i−1)·N _(c) +i·N _(c+1) +n _(CCE,1) +N_(PUCCH) ^((q)),

wherein n_(PUCCH,i) ^((l)) is a PUCCH resource index determined based onresources used in transmission of PDCCHs corresponding to the PDSCHsreceived in the DL subframe that is the ^(i)th element of the q^(th)subset, M_(q) is the total number of DL subframes in the q^(t h) subset,0≦i<M_(q), c is selected from {0,1,2,3} such thatN_(c)≦n_(CCE,i)<N_(c+1), N_(c)=max {0, └[N_(RB) ^(DL)·(N_(RB)^(DL)·c−4)]/36┘} where N_(RB) ^(DL) is the number of physical resourceblocks, PRBs, in each downlink subframe and where N_(sc) ^(RB) is thenumber of subcarriers in each physical resource block, n_(CCE,i) is thesequence number of the first Control Channel Element, CCE, used fortransmission of the corresponding PDCCH in subframe n−k_(i) ^((q)),k_(i) ^((q)) (q=0,1) is the i^(th) element of the q^(th) subset, nindicates the UL subframe associated with the DL subframes where theplurality of PDSCHs are received, N hd PUCCH^((q)) (q=0,1) is an offsetfor q^(th) subset, wherein q=0 corresponds to one of the first andsecond subsets of DL subframes and q=1 corresponds to the other one ofthe first and second subsets of DL subframes.

As above, there may be an offset between the first set of PUCCH resourceindices and the second set of PUCCH resource indices.

As above, the offset may be configured by higher layers or predefined.

As above, the second subset of DL subframes may comprise all the DLsubframes indicated by the DL reference TDD configuration other than DLsubframes of the first subset of DL subframes.

The processor 2640 may further be configured to add one or more virtualsubframes to the first subset of DL subframes. The one or more virtualsubframes may be used for assigning PUCCH resource indices, but not forreal PDSCH transmissions.

FIG. 27 is a schematic block diagram of a BS 2700 according to someembodiments of the present disclosure.

As shown, BS 2700 includes a receiver 2710, a transmitter 2720, a memory2730 and a processor 2740. The memory 2730 is configured to store TDDconfigurations, e.g., TDD configurations 0-6. The processor 2740 isconfigured to control, e.g., according to instructions stored in thememory 2730, the transmitter 2720 to transmit a plurality of PDSCHs inDL subframes associated with an UL subframe and indicated by a DLreference TDD configuration. The processor 2740 is also configured tocontrol, e.g., according to instructions stored in the memory 2730, thereceiver 2710 to, for each of the transmitted PDSCHs, receive HARQACK/NACK at least partially on PUCCH resources indicated by DCI and/orRRC signaling.

Alternatively or additionally, the processor 2740 may be configured todivide the DL subframes into a first subset of DL subframes and a secondsubset of DL subframes. The first subset of DL subframes is according tothis example also indicated by an UL reference TDD configuration. Theprocessor 2740 may further be configured to assign a set of PUCCHresource indices based on resources used in transmission of PDCCHscorresponding to the PDSCHs transmitted in the DL subframes of the firstsubset of DL subframes. In this case, the processor 2740 may also beconfigured to control, e.g., according to instructions stored in thememory 2730, the receiver 2710 to, for each of the PDSCHs transmitted inthe DL subframe of the first subset of DL subframes, receive HARQACK/NACK on PUCCH resources in an order of the assigned set of PUCCHresource indices. Finally, the processor 2740 may be configured tocontrol, e.g., according to instructions stored in the memory 2730, thereceiver 2710 to, for each of the PDSCHs received in the DL subframes ofthe second subset of DL subframes, receive HARQ ACK/NACK on PUCCHresources indicated by DCI and/or RRC signaling.

As above, the second subset of DL subframes may comprise all the DLsubframes indicated by the DL reference TDD configuration other than DLsubframes of the first subset of DL subframes.

The processor 2740 may further be configured to add one or more virtualsubframes to the first subset of DL subframes. The one or more virtualsubframes may be used for assigning PUCCH resource indices, but not forreal PDSCH transmissions.

FIG. 28 is a schematic block diagram of a BS 2800 according to someembodiments of the present disclosure.

As shown, BS 2800 includes a receiver 2810, a transmitter 2820, a memory2830 and a processor 2840. The memory 2830 is configured to store TDDconfigurations, e.g., TDD configurations 0-6. The processor 2840 isconfigured to control, e.g., according to instructions stored in thememory 2830, the transmitter 2820 to transmit a plurality of PDSCHs inDL subframes associated with an UL subframe and indicated by a DLreference TDD configuration. The processor 2840 is further configured todetermine, for each of the transmitted PDSCHs, a PUCCH resource based onresources used in transmission of PDCCHs corresponding to the PDSCHstransmitted in the corresponding DL subframe (e.g., the sequence numberof the first CCE used for transmission of PDCCHs corresponding to thetransmitted PDSCH in the corresponding DL subframe) and a start positionof the PUCCH resource corresponding to the DL subframe. The processor2840 is also configured to control, e.g., according to instructionsstored in the memory 2830, the receiver 2810 to, for each of thetransmitted PDSCHs, receive HARQ ACK/NACK on the determined PUCCHresource.

As above, the start position may be configured by higher layers orpredefined.

As above, the start position may be configured using related informationinformed by broadcasting, RRC signaling, or MAC CE.

FIG. 29 is a schematic block diagram of a BS 2900 according to someembodiments of the present disclosure.

As shown, BS 2900 includes a receiver 2910, a transmitter 2920, a memory2930 and a processor 2940. The memory 2930 is configured to store TDDconfigurations, e.g., TDD configurations 0-6. The processor 2940 isconfigured to control, e.g., according to instructions stored in thememory 2930, the transmitter 2920 to transmit a plurality of PDSCHs inDL subframes associated with an UL subframe and indicated by a DLreference TDD configuration. The processor 2940 is further configured toselect a DL subframe of the DL subframes to be a first DL subframe. Thesequence number of the selected DL subframe is the same as that of afirst DL subframe of DL subframes associated with the UL subframe butindicated by an UL reference TDD configuration. The processor 2940 isfurther configured to assign PUCCH resource indices based on resourcesused in transmission of PDCCHs corresponding to the PDSCHs transmittedin the DL subframes associated with the UL subframe and indicated by theDL reference TDD configuration. The PUCCH resource indices are assignedin an order starting from the selected first DL subframe of the DLsubframes associated with the UL subframe and indicated by the DLreference TDD configuration. The processor 2940 is further configured tocontrol, e.g., according to instructions stored in the memory 2930, thereceiver 2910 to, for each of the transmitted PDSCHs, receive HARQACK/NACK on PUCCH resources in the order of the assigned PUCCH resourceindices.

As described in the above embodiments, the PUCCH HARQ-ACK resourceconflict problem caused by dynamic TDD configuration is solved, whileefficiently compressing PUCCH HARQ-ACK resource to improve the resourceutilization efficiency.

Although the present technology has been described above with referenceto specific embodiments, it is not intended to be limited to thespecific form set forth herein. For example, the embodiments presentedhere are not limited to scenarios with PDCCH; rather they are equallyapplicable to other scenarios with e.g., ePDCCH (Enhanced PDCCH). Forexample, the embodiments presented herein are not limited to theexisting TDD configuration; rather they are equally applicable to newTDD configurations defined in future. For example, the embodimentspresented herein are noted limited to the eNB; rather they are equallyapplicable to various types of base stations. The technology is limitedonly by the accompanying claims and other embodiments than the specificones described above are equally possible within the scope of theappended claims. As used herein, the terms “comprise/comprises” or“include/includes” do not exclude the presence of other elements orsteps. Furthermore, although individual features may be included indifferent claims, these may possibly advantageously be combined, and theinclusion of different claims does not imply that a combination offeatures is not feasible and/or advantageous. In addition, singularreferences do not exclude a plurality. Finally, reference signs in theclaims are provided merely as a clarifying example and should not beconstrued as limiting the scope of the claims in any way.

1.-56. (canceled)
 57. A method used in a User Equipment, UE, forreporting Hybrid Automatic Repeat Request, HARQ, acknowledgement,ACK,/non-acknowledgement, NACK, for Physical Downlink Shared Channels,PDSCHs, in dynamic time division duplex, TDD, configurations, the methodcomprising: receiving a plurality of PDSCHs in DownLink, DL, subframesassociated with an UpLink, UL, subframe and indicated by a DL referenceTDD configuration; dividing the DL subframes into a first subset of DLsubframes and a second subset of DL subframes, wherein the first subsetof DL subframes is also indicated by an UL reference TDD configuration;assigning a first set of Physical Uplink Control Channel, PUCCH,resource indices based on resources used in transmission of PhysicalDownlink Control Channels, PDCCHs, corresponding to the PDSCHs receivedin the DL subframes of the first subset of DL subframes; assigning asecond set of PUCCH resource indices based on resources used intransmission of PDCCHs corresponding to the PDSCHs received in the DLsubframes of the second subset of DL subframes; and for each of thereceived PDSCHs, reporting HARQ ACK/NACK using PUCCH resources in anorder of the assigned first set of PUCCH resource indices for PDSCHsreceived in the DL subframes of the first subset of DL subframes and inan order of the assigned second set of PUCCH resource indices for PDSCHsreceived in the DL subframes of the second subset of DL subframes,characterized in that assigning the first set of PUCCH resource indicesand the second set of PUCCH resource indices are based on the followingformula:n _(PUCCH,i) ^((l))=(M _(q) i−1)·N_(c) +i·N _(c+1) +n _(CCE,i) +N_(PUCCH) ^((q)), wherein n_(PUCCH,i) ⁽¹⁾ is a PUCCH resource indexdetermined based on resources used in transmission of PDCCHscorresponding to the PDSCHs received in the DL subframe that is thei^(th) element of the q^(th) subset, M_(q) is the total number of DLsubframes in the q^(th) subset, 0≦i<M_(q), c is selected from {0,1,2,3}such that N_(c)≦n_(CCE,i)<N_(c+1), N_(c)=max {0, └[N_(RB) ^(DL·(N) _(sc)^(RB)·c−4)]/36┘} where N_(RB) ^(DL) is the number of physical resourceblocks, PRBs, in each downlink subframe and where N_(sc) ^(RB) is thenumber of subcarriers in each physical resource block, n_(CCE), is thesequence number of the first Control Channel Element, CCE, used fortransmission of the corresponding PDCCH in subframe n−k_(i) ^((q)),k_(i) ^((q)) (q=0,1) is the i ^(th) element of the q^(th) subset, nindicates the UL subframe associated with the DL subframes where theplurality of PDSCHs are received, N_(PUCCH) ^((q)) ((q=0,1) is an offsetfor q^(th) subset, wherein q=0 corresponds to one of the first andsecond subsets of DL subframes and q=1 corresponds to the other one ofthe first and second subsets of DL subframes.
 58. The method accordingto claim 57, wherein the second subset of DL subframes comprises all theDL subframes indicated by the DL reference TDD configuration other thanDL subframes of the first subset of DL subframes.
 59. The methodaccording to claim 57, wherein the first subset of DL subframescomprises one or more virtual subframes that are added by the UE,wherein the one or more virtual subframes are used for assigning PUCCHresource indices, but not for real PDSCH transmissions.
 60. A UserEquipment, UE, for reporting Hybrid Automatic Repeat Request, HARQ,acknowledgement, ACK,/non-acknowledgement, NACK, for Physical DownlinkShared Channels, PDSCHs, in dynamic time division duplex, TDD,configurations, the UE comprising a receiver, a transmitter, a memory aprocessor, wherein the memory is configured to store TDD configurations;the processor is configured to control the receiver to receive aplurality of PDSCHs in DownLink, DL, subframes associated with anUpLink, UL, subframe and indicated by a DL reference TDD configuration;the processor is configured to divide the DL subframes into a firstsubset of DL subframes and a second subset of DL subframes, wherein thefirst subset of DL subframes is also indicated by an UL reference TDDconfiguration; the processor is configured to assign a first set ofPhysical Uplink Control Channel, PUCCH, resource indices based onresources used in transmission of Physical Downlink Control Channels,PDCCHs, corresponding to the PDSCHs received in the DL subframes of thefirst subset of DL subframes; the processor is configured to assign asecond set of PUCCH resource indices based on resources used intransmission of PDCCHs corresponding to the PDSCHs received in the DLsubframes of the second subset of DL subframes; and the processor isconfigured to control the transmitter to, for each of the receivedPDSCHs, report HARQ ACK/NACK using PUCCH resources in an order of theassigned first set of PUCCH resource indices for PDSCHs received in theDL subframes of the first subset of DL subframes and in an order of theassigned second set of PUCCH resource indices for PDSCHs received in theDL subframes of the second subset of DL subframes, characterized in thatthe processor is configured to assign the first set of PUCCH resourceindices and the second set of PUCCH resource indices based on thefollowing formula:n _(PUCCH,i) ⁽¹⁾=(M _(q) −i−1)·N _(c) +i·N _(c+1) +n _(CCE,i)+N_(PUCCH)^((q)), wherein n_(PUCCH,i) ⁽¹⁾ is a PUCCH resource index determinedbased on resources used in transmission of PDCCHs corresponding to thePDSCHs received in the DL subframe that is the i^(th) element of theq^(th) subset, M^(q) is the total number of DL subframes in the q^(th)subset, 0≦i<M_(q), c is selected from {0,1,2,3} such thatN_(c)≦n_(CCE,i)<N_(c+1), N_(c)=max {0,└[N_(RB) ^(DL)·(N_(sc)^(RB)·c−4)]/36┘} where N_(RB) ^(DL) is the number of physical resourceblocks, PRBs, in each downlink subframe and where N_(sc) ^(RB) is thenumber of subcarriers in each physical resource block, n_(CCE,i) is thesequence number of the first Control Channel Element, CCE, used fortransmission of the corresponding PDCCH in subframe n−k_(i) ^((q)),k_(i) ^((q)) (q=0,1) is the i^(th) element of the q^(th) subset, nindicates the UL subframe associated with the DL subframes where theplurality of PDSCHs are received, N_(PUCCH) ^((q)) (q=0,1) is an offsetfor q^(th) subset, wherein q=0 corresponds to one of the first andsecond subsets of DL subframes and q=1 corresponds to the other one ofthe first and second subsets of DL subframes.
 61. The UE according toclaim 60, wherein the second subset of DL subframes comprises all the DLsubframes indicated by the DL reference TDD configuration other than DLsubframes of the first subset of DL subframes.
 62. The UE according toclaim 60, wherein the processor is further configured to add one or morevirtual subframes to the first subset of DL subframes, wherein the oneor more virtual subframes are used for assigning PUCCH resource indices,but not for real PDSCH transmissions.
 63. A method used in a BaseStation, BS, for receiving Hybrid Automatic Repeat Request, HARQ,acknowledgement, ACK,/non-acknowledgement, NACK, for Physical DownlinkShared Channels, PDSCHs, in dynamic time division duplex, TDD,configurations, the method comprising: transmitting a plurality ofPDSCHs in DownLink, DL, subframes associated with an UpLink, UL,subframe and indicated by a DL reference TDD configuration; dividing theDL subframes into a first subset of DL subframes and a second subset ofDL subframes, wherein the first subset of DL subframes is also indicatedby an UL reference TDD configuration; assigning a first set of PhysicalUplink Control Channel, PUCCH, resource indices based on resources usedin transmission of Physical Downlink Control Channels, PDCCHs,corresponding to the PDSCHs transmitted in the DL subframes of the firstsubset of DL subframes; assigning a second set of PUCCH resource indicesbased on resources used in transmission of PDCCHs corresponding to thePDSCHs transmitted in the DL subframes of the second subset of DLsubframes; and for each of the transmitted PDSCHs, receiving HARQACK/NACK on PUCCH resources in an order of the assigned first set ofPUCCH resource indices for PDSCHs transmitted in the DL subframes of thefirst subset of DL subframes and in an order of the assigned second setof PUCCH resource indices for PDSCHs transmitted in the DL subframes ofthe second subset of DL subframes, characterized in that assigning thefirst set of PUCCH resource indices and the second set of PUCCH resourceindices are based on the following formula:n _(PUCCH,i) ⁽¹⁾=(M _(q) −i−1)·N _(c) +i·N _(c+1) +n _(CCE,i) +N_(PUCCH) ^((q)), wherein n_(PUCCH,i) ⁽¹⁾ is a PUCCH resource indexdetermined based on resources used in transmission of PDCCHscorresponding to the PDSCHs received in the DL subframe that is thei^(th) element of the q^(th) subset, M_(q) is the total number of DLsubframes in the q^(th) subset, 0≦i<M_(q), c is selected from {0,1,2,3}such that N_(c)=max {0, └[N_(RB) ^(DL·() N _(sc) ^(RB·c−)4)]/36]} is thenumber of physical resource blocks, PRBs, in each downlink subframe andwhere N_(sc) ^(RB) is the number of subcarriers in each physicalresource block, n_(CCE,i) is the sequence number of the first ControlChannel Element, CCE, used for transmission of the corresponding PDCCHin subframe n−k_(i) ^((q)), k_(i) ^((q)) (q=0.1) is the i^(th) elementof the q^(th) subset, n indicates the UL subframe associated with the DLsubframes where the plurality of PDSCHs are received, N_(PUCCH)^((q))(q=0,1) is an offset for q^(th) subset, wherein q=0 corresponds toone of the first and second subsets of DL subframes and q=1 correspondsto the other one of the first and second subsets of DL subframes. 64.The method according to claim 63, wherein the second subset of DLsubframes comprises all the DL subframes indicated by the DL referenceTDD configuration other than DL subframes of the first subset of DLsubframes.
 65. The method according to claim 63, wherein the firstsubset of DL subframes comprises one or more virtual subframes that areadded by the BS, wherein the one or more virtual subframes are used forassigning PUCCH resource indices, but not for real PDSCH transmissions.66. A Base Station, BS, for receiving Hybrid Automatic Repeat Request,HARQ, acknowledgement, ACK,/non-acknowledgement, NACK, for PhysicalDownlink Shared Channels, PDSCHs, in dynamic time division duplex, TDD,configurations, the BS comprising a receiver, a transmitter, a memoryand a processor, wherein the memory is configured to store TDDconfigurations; the processor is configured to control the transmitterto transmit a plurality of PDSCHs in DownLink, DL, subframes associatedwith an UpLink, UL, subframe and indicated by a DL reference TDDconfiguration; the processor is configured to divide the DL subframesinto a first subset of DL subframes and a second subset of DL subframes,wherein the first subset of DL subframes is also indicated by an ULreference TDD configuration; the processor is configured to assign afirst set of Physical Uplink Control Channel, PUCCH, resource indicesbased on resources used in transmission of Physical Downlink ControlChannels, PDCCHs, corresponding to the PDSCHs transmitted in the DLsubframes of the first subset of DL subframes; the processor isconfigured to assign a second set of PUCCH resource indices based onresources used in transmission of PDCCHs corresponding to the PDSCHstransmitted in the DL subframes of the second subset of DL subframes;and the processor is configured to control the receiver to, for each ofthe transmitted PDSCHs, receive HARQ ACK/NACK on PUCCH resources in anorder of the assigned first set of PUCCH resource indices for PDSCHstransmitted in the DL subframes of the first subset of DL subframes andin an order of the assigned second set of PUCCH resource indices forPDSCHs transmitted in the DL subframes of the second subset of DLsubframes, characterized in that the processor is configured to assignthe first set of PUCCH resource indices and the second set of PUCCHresource indices based on the following formula:n _(PUCCH,i) ⁽¹⁾=(M _(q) −i1)·N _(c) +i·N _(c+1) +n _(CCE,i) +N _(PUCCH)^((q)), wherein n_(PUCCH,i) ⁽¹⁾ is a PUCCH resource index determinedbased on resources used in transmission of PDCCHs corresponding to thePDSCHs received in the DL subframe that is the i^(th) element of theq^(th) subset, M_(q) is the total number of DL subframes in the q^(th)subset, 0≦i<M_(q), c is selected from {0,1,2,3} such thatN_(c)≦n_(CCE,i)<N_(c+1), N_(c)=max {0, └[N_(RB) ^(DL)·(N_(sc)^(RB)·c−4)]/36┘} where N_(RB) ^(DL) is the number of physical resourceblocks, PRBs, in each downlink subframe and where N_(sc) ^(RB) is thenumber of subcarriers in each physical resource block, n_(CCE,i) is thesequence number of the first Control Channel Element, CCE, used fortransmission of the corresponding PDCCH in subframe n−k_(i) ^((q)),k_(i) ^((q)) (q=0,1) is the i^(th) element of the q^(th) subset, nindicates the UL subframe associated with the DL subframes where theplurality of PDSCHs are received, N_(PUCCH) ^((q)) (q=0,1) is an offsetfor q^(th) subset, wherein q=0 corresponds to one of the first andsecond subsets of DL subframes and q=1 corresponds to the other one ofthe first and second subsets of DL subframes.
 67. The BS according toclaim 66, wherein the second subset of DL subframes comprises all the DLsubframes indicated by the DL reference TDD configuration other than DLsubframes of the first subset of DL subframes.
 68. The BS according toclaim 66, wherein the processor is further configured to add one or morevirtual subframes to the first subset of DL subframes, wherein the oneor more virtual subframes are used for assigning PUCCH resource indices,but not for real PDSCH transmissions.